diff --git a/packages/backend/src/prelude/symbol.ts b/packages/backend/src/prelude/symbol.ts
deleted file mode 100644
index 5b88467d46..0000000000
--- a/packages/backend/src/prelude/symbol.ts
+++ /dev/null
@@ -1 +0,0 @@
-export const fallback = Symbol("fallback");
diff --git a/packages/backend/src/services/chart/charts/test-grouped.ts b/packages/backend/src/services/chart/charts/test-grouped.ts
deleted file mode 100644
index 6520099fe6..0000000000
--- a/packages/backend/src/services/chart/charts/test-grouped.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-import type { KVs } from "../core.js";
-import Chart from "../core.js";
-import { name, schema } from "./entities/test-grouped.js";
-
-/**
- * For testing
- */
-
-export default class TestGroupedChart extends Chart<typeof schema> {
-	private total = {} as Record<string, number>;
-
-	constructor() {
-		super(name, schema, true);
-	}
-
-	protected async tickMajor(
-		group: string,
-	): Promise<Partial<KVs<typeof schema>>> {
-		return {
-			"foo.total": this.total[group],
-		};
-	}
-
-	protected async tickMinor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	public async increment(group: string): Promise<void> {
-		if (this.total[group] == null) this.total[group] = 0;
-
-		this.total[group]++;
-
-		await this.commit(
-			{
-				"foo.total": 1,
-				"foo.inc": 1,
-			},
-			group,
-		);
-	}
-}
diff --git a/packages/backend/src/services/chart/charts/test-intersection.ts b/packages/backend/src/services/chart/charts/test-intersection.ts
deleted file mode 100644
index 0fa973861f..0000000000
--- a/packages/backend/src/services/chart/charts/test-intersection.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-import type { KVs } from "../core.js";
-import Chart from "../core.js";
-import { name, schema } from "./entities/test-intersection.js";
-
-/**
- * For testing
- */
-
-export default class TestIntersectionChart extends Chart<typeof schema> {
-	constructor() {
-		super(name, schema);
-	}
-
-	protected async tickMajor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	protected async tickMinor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	public async addA(key: string): Promise<void> {
-		await this.commit({
-			a: [key],
-		});
-	}
-
-	public async addB(key: string): Promise<void> {
-		await this.commit({
-			b: [key],
-		});
-	}
-}
diff --git a/packages/backend/src/services/chart/charts/test-unique.ts b/packages/backend/src/services/chart/charts/test-unique.ts
deleted file mode 100644
index 095021622c..0000000000
--- a/packages/backend/src/services/chart/charts/test-unique.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-import type { KVs } from "../core.js";
-import Chart from "../core.js";
-import { name, schema } from "./entities/test-unique.js";
-
-/**
- * For testing
- */
-
-export default class TestUniqueChart extends Chart<typeof schema> {
-	constructor() {
-		super(name, schema);
-	}
-
-	protected async tickMajor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	protected async tickMinor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	public async uniqueIncrement(key: string): Promise<void> {
-		await this.commit({
-			foo: [key],
-		});
-	}
-}
diff --git a/packages/backend/src/services/chart/charts/test.ts b/packages/backend/src/services/chart/charts/test.ts
deleted file mode 100644
index afdb3bf14e..0000000000
--- a/packages/backend/src/services/chart/charts/test.ts
+++ /dev/null
@@ -1,43 +0,0 @@
-import type { KVs } from "../core.js";
-import Chart from "../core.js";
-import { name, schema } from "./entities/test.js";
-
-/**
- * For testing
- */
-
-export default class TestChart extends Chart<typeof schema> {
-	public total = 0; // publicにするのはテストのため
-
-	constructor() {
-		super(name, schema);
-	}
-
-	protected async tickMajor(): Promise<Partial<KVs<typeof schema>>> {
-		return {
-			"foo.total": this.total,
-		};
-	}
-
-	protected async tickMinor(): Promise<Partial<KVs<typeof schema>>> {
-		return {};
-	}
-
-	public async increment(): Promise<void> {
-		this.total++;
-
-		await this.commit({
-			"foo.total": 1,
-			"foo.inc": 1,
-		});
-	}
-
-	public async decrement(): Promise<void> {
-		this.total--;
-
-		await this.commit({
-			"foo.total": -1,
-			"foo.dec": 1,
-		});
-	}
-}