diff --git a/acceptance/README.md b/acceptance/README.md
index 132e806..a81d887 100644
--- a/acceptance/README.md
+++ b/acceptance/README.md
@@ -33,5 +33,6 @@
 | Run Cache | `run-cache.feature` |
 | Source Intake and Fetching v0.1 | `source-intake-and-fetching.feature` |
 | Source Discovery v0.1 | `source-discovery.feature` |
+| Manual Source URL Intake v0.1 | `manual-source-url-intake.feature` |
 
 - source-quality-and-freshness.feature: Source quality/freshness indicators, unknown caveats, and report summary behavior
diff --git a/acceptance/manual-source-url-intake.feature b/acceptance/manual-source-url-intake.feature
new file mode 100644
index 0000000..1c7a209
--- /dev/null
+++ b/acceptance/manual-source-url-intake.feature
@@ -0,0 +1,25 @@
+Feature: Manual Source URL Intake
+
+  Scenario: User starts an investigation with optional source URLs
+    Given the user is on the TraceMap landing page
+    When the user enters a research topic
+    And the user enters one or more source URLs
+    And the user starts the investigation
+    Then a new analysis run should be created
+    And manual source URLs should be passed into source intake
+    And manual source URLs should be prioritized over discovered sources
+    And the run page should display the investigation result
+
+  Scenario: User enters duplicate source URLs
+    Given the user is on the TraceMap landing page
+    When the user enters duplicate source URLs
+    And the user starts the investigation
+    Then duplicate URLs should be removed before source intake
+    And the run should not fail because of duplicates
+
+  Scenario: User enters an invalid source URL
+    Given the user is on the TraceMap landing page
+    When the user enters an invalid source URL
+    And the user starts the investigation
+    Then the form should show a clear validation error
+    And no broken analysis run should be created
diff --git a/e2e/home.spec.ts b/e2e/home.spec.ts
index d9ca661..707ef12 100644
--- a/e2e/home.spec.ts
+++ b/e2e/home.spec.ts
@@ -14,4 +14,5 @@ test("home page and health endpoint are reachable", async ({ page, request }) =>
 
   await expect(page.getByRole("heading", { level: 1, name: "TraceMap" })).toBeVisible();
   await expect(page.getByRole("button", { name: "Start Investigation" })).toBeVisible();
+  await expect(page.getByTestId("manual-source-urls-input")).toBeVisible();
 });
diff --git a/specs/README.md b/specs/README.md
index 9e08cd9..5007536 100644
--- a/specs/README.md
+++ b/specs/README.md
@@ -44,5 +44,6 @@ Each feature spec should describe:
 | Run Cache | [run-cache.md](./run-cache.md) |
 | Source Intake and Fetching v0.1 | [source-intake-and-fetching.md](./source-intake-and-fetching.md) |
 | Source Discovery v0.1 | [source-discovery.md](./source-discovery.md) |
+| Manual Source URL Intake v0.1 | [manual-source-url-intake.md](./manual-source-url-intake.md) |
 
 - source-quality-and-freshness.md: Source Quality & Freshness Inspector v0.1 (derived quality signals, unknown caveats, report summary)
diff --git a/specs/manual-source-url-intake.md b/specs/manual-source-url-intake.md
new file mode 100644
index 0000000..28f37a5
--- /dev/null
+++ b/specs/manual-source-url-intake.md
@@ -0,0 +1,91 @@
+# Manual Source URL Intake v0.1
+
+## Purpose
+
+Allow users to submit optional source URLs from the landing page so Investigation Mission runs can prioritize user-specified references in source intake without changing the core answer/evidence pipeline.
+
+## User value
+
+- Users can seed investigations with known high-signal references (official IR, press releases, public docs, papers, government data).
+- Evidence Map traceability improves because user-intended sources are treated as first-class candidates.
+- Invalid input is blocked early with clear form feedback, preventing broken runs.
+
+## Scope
+
+- Add optional multi-line URL input (`sourceUrls`) on landing intake form.
+- Parse, validate, normalize, and deduplicate URLs in server action.
+- Pass valid manual URLs through run creation options to source intake.
+- Merge manual URLs with topic-extracted/discovered URLs, prioritizing manual URLs.
+- Keep OpenAI provider schema unchanged; continue using existing `sourceCandidates` path.
+- Keep existing Source Cache / Fetch Snapshot route for URL resolution.
+
+## Non-goals
+
+- RAG, embeddings, reranking, full-text crawling, PDF parsing.
+- Background jobs, streaming response.
+- New source tables, auth/workspace changes, upload flows.
+- Large OpenAI provider schema redesign.
+
+## Existing implementation constraints
+
+- `AnalysisRun.question` is not renamed in this slice.
+- `question` form field remains required and unchanged.
+- Investigation mode selector behavior remains unchanged.
+- Existing Evidence Map / Unknown Map / Source Lineage / Briefing Report / Report Export Lite must keep working.
+
+## Data model strategy
+
+- No Prisma schema changes and no DB migration.
+- Manual URLs are transient form input passed via server-side options.
+- Source candidate persistence continues via existing `source_snapshots` and source cache/fetch snapshot linkage.
+
+## UI requirements
+
+- Add textarea between Research topic and Investigation depth.
+- Label: `Optional source URLs`.
+- Help text: `Add one URL per line. TraceMap will prioritize these sources when building the evidence map.`
+- Name: `sourceUrls`.
+- `data-testid="manual-source-urls-input"`.
+- Optional input, empty means existing behavior.
+- Validation error can be shown near existing form error region.
+
+## Server action requirements
+
+- Read `sourceUrls` from `FormData`.
+- Split by line, trim, drop empty lines.
+- Validate as absolute `http(s)` URLs.
+- Normalize and dedupe before forwarding.
+- On invalid line(s), return form error and do not create run.
+- Error message: `Source URLs must be valid http(s) URLs, one per line.`
+
+## Source intake requirements
+
+- Accept `manualSourceUrls` option in `buildSourceIntakeFromQuestion`.
+- Merge URL inputs in this precedence order:
+  1) manual source URLs,
+  2) URLs extracted from question text,
+  3) discovery provider URLs.
+- Deduplicate by normalized URL while preserving higher-priority origin.
+- Invalid URLs should be safely reported into `ignoredUrls` if they still reach intake.
+
+## Provider requirements
+
+- OpenAI provider schema remains unchanged.
+- Manual URLs are surfaced only via existing `sourceCandidates` context.
+- Optional prompt tweak may prefer user-provided candidates, but no large prompt inflation.
+
+## Cache requirements
+
+- Manual URLs can change output; avoid stale run-cache reuse.
+- For v0.1 safety: skip run-cache lookup/store when `manualSourceUrls` are present.
+
+## Test requirements
+
+- Unit tests for manual URL parser/validator normalization + dedupe.
+- Server action behavior for valid/invalid/manual-empty paths.
+- Source intake merge priority and duplicate removal coverage.
+- Existing tests remain green.
+
+## Acceptance references
+
+- `acceptance/manual-source-url-intake.feature`
diff --git a/src/app/actions/create-run.ts b/src/app/actions/create-run.ts
index b408166..a4e8a1e 100644
--- a/src/app/actions/create-run.ts
+++ b/src/app/actions/create-run.ts
@@ -5,6 +5,7 @@ import { redirect } from "next/navigation";
 
 import { resolveInvestigationMode } from "@/server/analysis/investigation-limits";
 import { createAnalysisRunFromProvider } from "@/server/analysis/create-analysis-run-from-provider";
+import { parseManualSourceUrls } from "@/app/actions/manual-source-urls";
 
 export type CreateRunFormState = {
   error?: string;
@@ -24,6 +25,14 @@ export async function createMockRunAction(
     typeof rawMode === "string" ? rawMode : undefined,
   );
 
-  const runId = await createAnalysisRunFromProvider(raw.trim(), { mode });
+  const manualSourceUrlsResult = parseManualSourceUrls(formData.get("sourceUrls"));
+  if (manualSourceUrlsResult.kind === "error") {
+    return { error: manualSourceUrlsResult.message };
+  }
+
+  const runId = await createAnalysisRunFromProvider(raw.trim(), {
+    mode,
+    manualSourceUrls: manualSourceUrlsResult.manualSourceUrls,
+  });
   redirect(`/runs/${runId}` as Route);
 }
diff --git a/src/app/actions/manual-source-urls.ts b/src/app/actions/manual-source-urls.ts
new file mode 100644
index 0000000..e031d9f
--- /dev/null
+++ b/src/app/actions/manual-source-urls.ts
@@ -0,0 +1,30 @@
+import { normalizeSourceUrl } from "@/server/analysis/source-url-normalization";
+
+export const MANUAL_SOURCE_URLS_ERROR_MESSAGE =
+  "Source URLs must be valid http(s) URLs, one per line.";
+
+export type ParseManualSourceUrlsResult =
+  | { kind: "ok"; manualSourceUrls: string[] }
+  | { kind: "error"; message: string };
+
+export function parseManualSourceUrls(raw: FormDataEntryValue | null): ParseManualSourceUrlsResult {
+  if (typeof raw !== "string" || raw.trim().length === 0) {
+    return { kind: "ok", manualSourceUrls: [] };
+  }
+
+  const lines = raw
+    .split(/\r?\n/)
+    .map((line) => line.trim())
+    .filter((line) => line.length > 0);
+
+  const unique = new Set<string>();
+  for (const line of lines) {
+    const normalized = normalizeSourceUrl(line);
+    if (normalized.kind !== "ok") {
+      return { kind: "error", message: MANUAL_SOURCE_URLS_ERROR_MESSAGE };
+    }
+    unique.add(normalized.normalizedUrl);
+  }
+
+  return { kind: "ok", manualSourceUrls: [...unique] };
+}
diff --git a/src/features/landing/components/question-intake.tsx b/src/features/landing/components/question-intake.tsx
index 6a332fe..9863375 100644
--- a/src/features/landing/components/question-intake.tsx
+++ b/src/features/landing/components/question-intake.tsx
@@ -48,6 +48,7 @@ export function QuestionIntake() {
         />
         <div className="muted" data-testid="research-topic-examples" style={{ marginTop: "0.6rem" }}>
           <p>Examples:</p>
+          <p style={{ marginTop: "0.35rem" }}>公式URLを貼ると、根拠確認と出典追跡がしやすくなります。</p>
           <ul style={{ marginTop: "0.35rem", paddingLeft: "1rem" }}>
             <li>トヨタ自動車のEV戦略について、成長要因・リスク・競合状況・未確認事項を根拠付きで整理する</li>
             <li>国内生成AI市場の主要プレイヤーを比較し、公開情報ベースで市場機会と不明点を整理する</li>
@@ -55,6 +56,22 @@ export function QuestionIntake() {
             <li>中小企業向けSaaS市場で、Vertical SaaSが伸びる要因とリスクを調査する</li>
           </ul>
         </div>
+        <label className="question-label" htmlFor="sourceUrls" style={{ marginTop: "1rem" }}>
+          Optional source URLs
+        </label>
+        <p className="muted" style={{ marginTop: "0.25rem", marginBottom: "0.5rem" }}>
+          Add one URL per line. TraceMap will prioritize these sources when building the evidence map.
+        </p>
+        <textarea
+          id="sourceUrls"
+          name="sourceUrls"
+          placeholder={`https://example.com/official-report
+https://example.com/press-release
+https://example.com/technical-doc`}
+          rows={4}
+          disabled={isPending}
+          data-testid="manual-source-urls-input"
+        />
         <label className="question-label" htmlFor="mode" style={{ marginTop: "1rem" }}>
           Investigation depth
         </label>
diff --git a/src/server/analysis/create-analysis-run-from-provider.ts b/src/server/analysis/create-analysis-run-from-provider.ts
index 7ef1d9e..2add203 100644
--- a/src/server/analysis/create-analysis-run-from-provider.ts
+++ b/src/server/analysis/create-analysis-run-from-provider.ts
@@ -16,6 +16,7 @@ import type { InvestigationMode } from "@/server/analysis/investigation-limits";
 
 export type CreateAnalysisRunOptions = {
   mode?: InvestigationMode;
+  manualSourceUrls?: string[];
 };
 
 /**
@@ -31,6 +32,8 @@ export async function createAnalysisRunFromProvider(
     options.mode ?? process.env.TRACEMAP_INVESTIGATION_MODE?.trim(),
   );
 
+  const hasManualSourceUrls = (options.manualSourceUrls?.length ?? 0) > 0;
+
   const run = await prisma.analysisRun.create({
     data: {
       question,
@@ -53,8 +56,9 @@ export async function createAnalysisRunFromProvider(
   let payload: GeneratedAnswerGraphPayload | null = null;
   let shouldStoreRunCache = false;
 
-  try {
-    const cached = await lookupRunCacheEntry(cacheKeyInfo);
+  if (!hasManualSourceUrls) {
+    try {
+      const cached = await lookupRunCacheEntry(cacheKeyInfo);
     if (cached.kind === "hit") {
       console.info("[analysis] run cache hit", {
         runId: run.id,
@@ -69,17 +73,20 @@ export async function createAnalysisRunFromProvider(
         reason: cached.reason,
       });
     }
-  } catch (cause) {
-    console.error("[analysis] run cache lookup failed", {
-      runId: run.id,
-      cause,
-    });
+    } catch (cause) {
+      console.error("[analysis] run cache lookup failed", {
+        runId: run.id,
+        cause,
+      });
+    }
   }
 
   if (payload === null) {
     let sourceIntake: SourceIntakeResult = { candidates: [], ignoredUrls: [] };
     try {
-      sourceIntake = await buildSourceIntakeFromQuestion(question);
+      sourceIntake = await buildSourceIntakeFromQuestion(question, {
+        manualSourceUrls: options.manualSourceUrls ?? [],
+      });
     } catch (cause) {
       console.error("[analysis] source intake failed", { runId: run.id, cause });
     }
@@ -152,7 +159,7 @@ export async function createAnalysisRunFromProvider(
     } satisfies Prisma.AnalysisRunUpdateInput,
   });
 
-  if (shouldStoreRunCache) {
+  if (shouldStoreRunCache && !hasManualSourceUrls) {
     try {
       await storeRunCacheEntry({ cacheKeyInfo, payload });
       console.info("[analysis] run cache stored", {
diff --git a/src/server/analysis/source-intake/source-intake-service.ts b/src/server/analysis/source-intake/source-intake-service.ts
index d90ce61..6fcc125 100644
--- a/src/server/analysis/source-intake/source-intake-service.ts
+++ b/src/server/analysis/source-intake/source-intake-service.ts
@@ -2,10 +2,21 @@ import type { SourceCandidate, SourceIntakeResult } from "@/types/source-intake"
 import { resolveSourceCacheForUrl } from "@/server/analysis/source-cache-service";
 import { extractUrls } from "@/server/analysis/source-intake/extract-urls";
 import { resolveSourceDiscoveryProvider } from "@/server/analysis/source-discovery/resolve-source-discovery-provider";
-import { DEFAULT_DISCOVERY_MAX_RESULTS, DEFAULT_SOURCE_CANDIDATE_MAX_RESULTS } from "@/server/analysis/source-discovery/source-discovery-service";
+import {
+  DEFAULT_DISCOVERY_MAX_RESULTS,
+  DEFAULT_SOURCE_CANDIDATE_MAX_RESULTS,
+} from "@/server/analysis/source-discovery/source-discovery-service";
 
-export async function buildSourceIntakeFromQuestion(question: string): Promise<SourceIntakeResult> {
-  const manualUrls = extractUrls(question);
+export type BuildSourceIntakeOptions = {
+  manualSourceUrls?: string[];
+};
+
+export async function buildSourceIntakeFromQuestion(
+  question: string,
+  options: BuildSourceIntakeOptions = {},
+): Promise<SourceIntakeResult> {
+  const topicUrls = extractUrls(question);
+  const manualUrls = options.manualSourceUrls ?? [];
   const discoveryProvider = resolveSourceDiscoveryProvider();
   const ignoredUrls: SourceIntakeResult["ignoredUrls"] = [];
 
@@ -24,6 +35,7 @@ export async function buildSourceIntakeFromQuestion(question: string): Promise<S
 
   const merged = [
     ...manualUrls.map((url) => ({ url, origin: "manual_url" as const })),
+    ...topicUrls.map((url) => ({ url, origin: "topic_url" as const })),
     ...discoveredUrls.map((url) => ({ url, origin: "discovered" as const })),
   ];
 
@@ -52,14 +64,19 @@ export async function buildSourceIntakeFromQuestion(question: string): Promise<S
       normalizedUrl: result.normalizedUrl,
       originalUrl: result.originalUrl,
       finalUrl: result.finalUrl,
-      label: result.finalUrl ? new URL(result.finalUrl).hostname : new URL(result.normalizedUrl).hostname,
+      label: result.finalUrl
+        ? new URL(result.finalUrl).hostname
+        : new URL(result.normalizedUrl).hostname,
       excerpt: result.excerpt,
       contentType: result.contentType,
       httpStatus: result.httpStatus,
       fetchedAt: result.checkedAt,
       sourceCacheEntryId: result.sourceCacheEntryId,
       sourceFetchSnapshotId: result.sourceFetchSnapshotId,
-      fetchErrorMessage: result.verificationStatus !== "verified" ? `verification_status:${result.verificationStatus}` : null,
+      fetchErrorMessage:
+        result.verificationStatus !== "verified"
+          ? `verification_status:${result.verificationStatus}`
+          : null,
       origin: item.origin,
     });
 
diff --git a/src/types/source-intake.ts b/src/types/source-intake.ts
index 632fa1e..7b52487 100644
--- a/src/types/source-intake.ts
+++ b/src/types/source-intake.ts
@@ -1,4 +1,4 @@
-export type SourceCandidateOrigin = "manual_url" | "discovered";
+export type SourceCandidateOrigin = "manual_url" | "topic_url" | "discovered";
 
 export type SourceCandidate = {
   normalizedUrl: string;
diff --git a/tests/manual-source-urls.test.ts b/tests/manual-source-urls.test.ts
new file mode 100644
index 0000000..b8b77d0
--- /dev/null
+++ b/tests/manual-source-urls.test.ts
@@ -0,0 +1,34 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  MANUAL_SOURCE_URLS_ERROR_MESSAGE,
+  parseManualSourceUrls,
+} from "@/app/actions/manual-source-urls";
+
+describe("parseManualSourceUrls", () => {
+  it("returns empty list for blank input", () => {
+    expect(parseManualSourceUrls(null)).toEqual({ kind: "ok", manualSourceUrls: [] });
+    expect(parseManualSourceUrls("   ")).toEqual({ kind: "ok", manualSourceUrls: [] });
+  });
+
+  it("normalizes and deduplicates urls by normalized form", () => {
+    const result = parseManualSourceUrls(
+      "https://Example.com/a?utm_source=x&k=1\nhttps://example.com/a?k=1#frag\nhttps://example.com/b",
+    );
+    expect(result.kind).toBe("ok");
+    if (result.kind === "ok") {
+      expect(result.manualSourceUrls).toEqual([
+        "https://example.com/a?k=1",
+        "https://example.com/b",
+      ]);
+    }
+  });
+
+  it("rejects invalid or non-http urls", () => {
+    const invalid = parseManualSourceUrls("not-a-url");
+    expect(invalid).toEqual({ kind: "error", message: MANUAL_SOURCE_URLS_ERROR_MESSAGE });
+
+    const ftp = parseManualSourceUrls("ftp://example.com/a");
+    expect(ftp).toEqual({ kind: "error", message: MANUAL_SOURCE_URLS_ERROR_MESSAGE });
+  });
+});
diff --git a/tests/source-intake-integration.test.ts b/tests/source-intake-integration.test.ts
index 287c304..6ecac3e 100644
--- a/tests/source-intake-integration.test.ts
+++ b/tests/source-intake-integration.test.ts
@@ -13,7 +13,7 @@ describe("buildSourceIntakeFromQuestion", () => {
     vi.mocked(resolveSourceCacheForUrl).mockResolvedValue({ kind: "resolved", normalizedUrl: "https://example.com/a", originalUrl: "https://example.com/a", finalUrl: "https://example.com/a", excerpt: null, contentType: "text/html", httpStatus: 200, checkedAt: new Date(), sourceCacheEntryId: "cache-1", sourceFetchSnapshotId: "snap-1", verificationStatus: "verified", contentHash: null, reusedCache: false });
     const { buildSourceIntakeFromQuestion } = await import("@/server/analysis/source-intake/source-intake-service");
     const result = await buildSourceIntakeFromQuestion("check https://example.com/a");
-    expect(result.candidates[0]?.origin).toBe("manual_url");
+    expect(result.candidates[0]?.origin).toBe("topic_url");
   });
 
   it("does not throw when brave discovery fails and records ignored discovery source", async () => {
@@ -43,4 +43,46 @@ describe("buildSourceIntakeFromQuestion", () => {
     expect(result.candidates).toHaveLength(1);
     expect(result.ignoredUrls).toContainEqual({ url: "[source_discovery]", reason: "missing key" });
   });
+  it("prioritizes manual urls over topic and discovered duplicates", async () => {
+    const { resolveSourceCacheForUrl } = await import("@/server/analysis/source-cache-service");
+    const { resolveSourceDiscoveryProvider } = await import("@/server/analysis/source-discovery/resolve-source-discovery-provider");
+    vi.mocked(resolveSourceDiscoveryProvider).mockReturnValue({
+      id: "mock",
+      discoverSources: vi.fn().mockResolvedValue({
+        kind: "success",
+        candidates: [
+          { url: "https://example.com/a", label: "A" },
+          { url: "https://example.com/c", label: "C" },
+        ],
+      }),
+    });
+
+    vi.mocked(resolveSourceCacheForUrl).mockImplementation(async (url: string) => ({
+      kind: "resolved",
+      normalizedUrl: url,
+      originalUrl: url,
+      finalUrl: url,
+      excerpt: null,
+      contentType: "text/html",
+      httpStatus: 200,
+      checkedAt: new Date(),
+      sourceCacheEntryId: `cache-${url}`,
+      sourceFetchSnapshotId: `snap-${url}`,
+      verificationStatus: "verified",
+      contentHash: null,
+      reusedCache: false,
+    }));
+
+    const { buildSourceIntakeFromQuestion } = await import("@/server/analysis/source-intake/source-intake-service");
+    const result = await buildSourceIntakeFromQuestion("topic has https://example.com/a", {
+      manualSourceUrls: ["https://example.com/a", "https://example.com/b"],
+    });
+
+    expect(result.candidates.map((candidate) => [candidate.normalizedUrl, candidate.origin])).toEqual([
+      ["https://example.com/a", "manual_url"],
+      ["https://example.com/b", "manual_url"],
+      ["https://example.com/c", "discovered"],
+    ]);
+  });
+
 });