diff --git a/frontend/src/components/NetworkGraph.bounded-label-summary.test.ts b/frontend/src/components/NetworkGraph.bounded-label-summary.test.ts
new file mode 100644
index 000000000..2b2b99881
--- /dev/null
+++ b/frontend/src/components/NetworkGraph.bounded-label-summary.test.ts
@@ -0,0 +1,24 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, it } from "vitest";
+
+function nodeLabelMemoSource(): string {
+  const source = readFileSync(new URL("./NetworkGraph.tsx", import.meta.url), "utf8");
+  const start = source.indexOf("  const nodeLabels = useMemo(() => {");
+  const end = source.indexOf("  const firstEdge =", start);
+
+  expect(start).toBeGreaterThanOrEqual(0);
+  expect(end).toBeGreaterThan(start);
+  return source.slice(start, end);
+}
+
+describe("NetworkGraph bounded label summary", () => {
+  it("caps label-summary work at five accepted labels without whole-array transforms", () => {
+    const memoSource = nodeLabelMemoSource();
+
+    expect(memoSource).toContain("for (const node of nodes)");
+    expect(memoSource).toContain("if (labels.length >= 5) break;");
+    expect(memoSource).not.toContain(".map(");
+    expect(memoSource).not.toContain(".filter(");
+    expect(memoSource).not.toContain(".slice(");
+  });
+});
diff --git a/frontend/src/components/NetworkGraph.label-boundary.test.tsx b/frontend/src/components/NetworkGraph.label-boundary.test.tsx
new file mode 100644
index 000000000..a7f2593ec
--- /dev/null
+++ b/frontend/src/components/NetworkGraph.label-boundary.test.tsx
@@ -0,0 +1,99 @@
+/* @vitest-environment jsdom */
+import React, { act } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const destroyMock = vi.fn();
+const fitMock = vi.fn();
+const moveToMock = vi.fn();
+const offMock = vi.fn();
+const onMock = vi.fn();
+const selectEdgesMock = vi.fn();
+const selectNodesMock = vi.fn();
+
+vi.mock("vis-network", () => ({
+  Network: vi.fn(function MockNetwork() {
+    return {
+      destroy: destroyMock,
+      fit: fitMock,
+      moveTo: moveToMock,
+      off: offMock,
+      on: onMock,
+      selectEdges: selectEdgesMock,
+      selectNodes: selectNodesMock,
+    };
+  }),
+}));
+
+import NetworkGraph from "./NetworkGraph";
+
+function jsonResponse(body: unknown) {
+  return {
+    ok: true,
+    json: async () => body,
+  };
+}
+
+async function flushAsyncWork() {
+  for (let index = 0; index < 5; index += 1) {
+    await act(async () => {
+      await Promise.resolve();
+      await new Promise((resolve) => setTimeout(resolve, 0));
+    });
+  }
+}
+
+describe("NetworkGraph label boundary", () => {
+  let root: Root | null = null;
+  let container: HTMLDivElement | null = null;
+
+  afterEach(() => {
+    if (root) {
+      act(() => root?.unmount());
+    }
+    root = null;
+    container?.remove();
+    container = null;
+    vi.unstubAllGlobals();
+    vi.clearAllMocks();
+  });
+
+  it("renders only the first five non-empty related-node labels in source order", async () => {
+    const fetchMock = vi.fn(() =>
+      Promise.resolve(
+        jsonResponse({
+          nodes: [
+            { id: "node-a", label: "A" },
+            { id: "empty-1", label: "" },
+            { id: "node-b", label: "B" },
+            { id: "node-c", label: "C" },
+            { id: "empty-2", label: "" },
+            { id: "node-d", label: "D" },
+            { id: "node-e", label: "E" },
+            { id: "node-f", label: "F" },
+          ],
+          edges: [],
+        }),
+      ),
+    );
+    vi.stubGlobal("fetch", fetchMock);
+
+    container = document.createElement("div");
+    document.body.appendChild(container);
+    root = createRoot(container);
+
+    await act(async () => {
+      root?.render(<NetworkGraph />);
+    });
+    await flushAsyncWork();
+
+    const summary = Array.from(container.querySelectorAll("p")).find((element) =>
+      element.textContent?.includes("관련 노드:"),
+    );
+
+    expect(summary?.textContent?.replace(/\s+/g, " ").trim()).toBe(
+      "관련 노드: A, B, C, D, E",
+    );
+    expect(summary?.textContent).not.toContain("F");
+  });
+});
diff --git a/frontend/src/components/NetworkGraph.tsx b/frontend/src/components/NetworkGraph.tsx
index 5bdfba9fa..03dad7cf7 100644
--- a/frontend/src/components/NetworkGraph.tsx
+++ b/frontend/src/components/NetworkGraph.tsx
@@ -278,10 +278,15 @@ export default function NetworkGraph() {
   }, [nodes, edges, nodeMap, edgeMap]);
 
   const nodeLabels = useMemo(() => {
-    return nodes
-      .map((node) => String(node.label ?? node.id))
-      .filter(Boolean)
-      .slice(0, 5);
+    const labels: string[] = [];
+    for (const node of nodes) {
+      const label = String(node.label ?? node.id);
+      if (label) {
+        labels.push(label);
+        if (labels.length >= 5) break;
+      }
+    }
+    return labels;
   }, [nodes]);
 
   const firstEdge = edges[0] ?? null;