diff --git a/packages/backend/src/server/api/openapi/gen-spec.ts b/packages/backend/src/server/api/openapi/gen-spec.ts
index fc6dadc23a..fc1e3081e1 100644
--- a/packages/backend/src/server/api/openapi/gen-spec.ts
+++ b/packages/backend/src/server/api/openapi/gen-spec.ts
@@ -38,7 +38,7 @@ export function genOpenapiSpec(config: Config) {
 		},
 	};
 
-	for (const [name, endpoint] of Object.entries(endpoints).filter(([name, ep]) => !ep.secure)) {
+	for (const [name, endpoint] of Object.entries(endpoints).filter(([name, ep]) => !('secure' in ep) || !ep.secure)) {
 		const errors = {} as any;
 
 		if ('errors' in endpoint && endpoint.errors) {
@@ -107,7 +107,7 @@ export function genOpenapiSpec(config: Config) {
 					content: {
 						'application/json': {
 							schema: {
-								$ref: '#/components/schemas/Error',
+								$ref: '#/components/schemas/ApiError',
 							},
 							examples: { ...errors, ...basicErrors['400'] },
 						},
@@ -118,7 +118,7 @@ export function genOpenapiSpec(config: Config) {
 					content: {
 						'application/json': {
 							schema: {
-								$ref: '#/components/schemas/Error',
+								$ref: '#/components/schemas/ApiError',
 							},
 							examples: basicErrors['401'],
 						},
@@ -129,7 +129,7 @@ export function genOpenapiSpec(config: Config) {
 					content: {
 						'application/json': {
 							schema: {
-								$ref: '#/components/schemas/Error',
+								$ref: '#/components/schemas/ApiError',
 							},
 							examples: basicErrors['403'],
 						},
@@ -140,7 +140,7 @@ export function genOpenapiSpec(config: Config) {
 					content: {
 						'application/json': {
 							schema: {
-								$ref: '#/components/schemas/Error',
+								$ref: '#/components/schemas/ApiError',
 							},
 							examples: basicErrors['418'],
 						},
@@ -152,7 +152,7 @@ export function genOpenapiSpec(config: Config) {
 						content: {
 							'application/json': {
 								schema: {
-									$ref: '#/components/schemas/Error',
+									$ref: '#/components/schemas/ApiError',
 								},
 								examples: basicErrors['429'],
 							},
@@ -164,7 +164,7 @@ export function genOpenapiSpec(config: Config) {
 					content: {
 						'application/json': {
 							schema: {
-								$ref: '#/components/schemas/Error',
+								$ref: '#/components/schemas/ApiError',
 							},
 							examples: basicErrors['500'],
 						},
diff --git a/packages/backend/src/server/api/openapi/schemas.ts b/packages/backend/src/server/api/openapi/schemas.ts
index bfffddbf88..1faf2bafc2 100644
--- a/packages/backend/src/server/api/openapi/schemas.ts
+++ b/packages/backend/src/server/api/openapi/schemas.ts
@@ -1,32 +1,5 @@
 import { refs } from 'misskey-js/built/schemas.js';
 
 export const schemas = {
-	Error: {
-		type: 'object',
-		properties: {
-			error: {
-				type: 'object',
-				description: 'An error object.',
-				properties: {
-					code: {
-						type: 'string',
-						description: 'An error code. Unique within the endpoint.',
-					},
-					message: {
-						type: 'string',
-						description: 'An error message.',
-					},
-					id: {
-						type: 'string',
-						format: 'uuid',
-						description: 'An error ID. This ID is static.',
-					},
-				},
-				required: ['code', 'id', 'message'],
-			},
-		},
-		required: ['error'],
-	},
-
 	...refs,
 };
diff --git a/packages/backend/test/e2e/antennas.ts b/packages/backend/test/e2e/antennas.ts
index dd3b09f85a..0065efeeb8 100644
--- a/packages/backend/test/e2e/antennas.ts
+++ b/packages/backend/test/e2e/antennas.ts
@@ -3,7 +3,6 @@ process.env.NODE_ENV = 'test';
 import * as assert from 'assert';
 import { inspect } from 'node:util';
 import { DEFAULT_POLICIES } from '@/core/RoleService.js';
-import type { Packed } from '@/misc/json-schema.js';
 import {
 	signup,
 	post,
@@ -19,6 +18,7 @@ import {
 } from '../utils.js';
 import type * as misskey from 'misskey-js';
 import type { INestApplicationContext } from '@nestjs/common';
+import { WeakSerialized } from 'schema-type';
 
 const compareBy = <T extends { id: string }>(selector: (s: T) => string = (s: T): string => s.id) => (a: T, b: T): number => {
 	return selector(a).localeCompare(selector(b));
@@ -28,12 +28,9 @@ describe('アンテナ', () => {
 	// エンティティとしてのアンテナを主眼においたテストを記述する
 	// (Antennaを返すエンドポイント、Antennaエンティティを書き換えるエンドポイント、Antennaからノートを取得するエンドポイントをテストする)
 
-	// BUG misskey-jsとjson-schemaが一致していない。
-	// - srcのenumにgroupが残っている
-	// - userGroupIdが残っている, isActiveがない
-	type Antenna = misskey.entities.Antenna | Packed<'Antenna'>;
-	type User = misskey.entities.MeDetailed & { token: string };
-	type Note = misskey.entities.Note;
+	type Antenna = WeakSerialized<misskey.entities.Antenna>;
+	type User = WeakSerialized<misskey.entities.MeDetailed & { token: string }>;
+	type Note = WeakSerialized<misskey.entities.Note>;
 
 	// アンテナを作成できる最小のパラメタ
 	const defaultParam = {
diff --git a/packages/backend/test/utils.ts b/packages/backend/test/utils.ts
index 1a4a0b3545..ca6c5d9f2b 100644
--- a/packages/backend/test/utils.ts
+++ b/packages/backend/test/utils.ts
@@ -10,6 +10,7 @@ import { DEFAULT_POLICIES } from '@/core/RoleService.js';
 import { entities } from '../src/postgres.js';
 import { loadConfig } from '../src/config.js';
 import type * as misskey from 'misskey-js';
+import { SchemaOrUndefined } from 'misskey-js/built/endpoints.types.js';
 
 export { server as startServer } from '@/boot/common.js';
 
@@ -25,15 +26,18 @@ export const api = async (endpoint: string, params: any, me?: any) => {
 	return await request(`api/${normalized}`, params, me);
 };
 
-export type ApiRequest = {
-	endpoint: string,
-	parameters: object,
+export type ApiRequest<X extends keyof misskey.Endpoints = keyof misskey.Endpoints, D extends misskey.Endpoints[X]['defines'][number] = misskey.Endpoints[X]['defines'][number], P extends D['req'] = D['req']> = {
+	endpoint: X,
+	parameters: SchemaOrUndefined<P>,
 	user: object | undefined,
 };
 
-export const successfulApiCall = async <T, >(request: ApiRequest, assertion: {
-	status?: number,
-} = {}): Promise<T> => {
+export const successfulApiCall = async <X extends keyof misskey.Endpoints, D extends misskey.Endpoints[X]['defines'][number] = misskey.Endpoints[X]['defines'][number]>(
+	request: ApiRequest<X, D>,
+	assertion: {
+		status?: number,
+	} = {}
+): Promise<SchemaOrUndefined<D['res']>> => {
 	const { endpoint, parameters, user } = request;
 	const res = await api(endpoint, parameters, user);
 	const status = assertion.status ?? (res.body == null ? 204 : 200);
@@ -41,11 +45,11 @@ export const successfulApiCall = async <T, >(request: ApiRequest, assertion: {
 	return res.body;
 };
 
-export const failedApiCall = async <T, >(request: ApiRequest, assertion: {
+export const failedApiCall = async <X extends keyof misskey.Endpoints>(request: ApiRequest<X>, assertion: {
 	status: number,
 	code: string,
 	id: string
-}): Promise<T> => {
+}): Promise<misskey.Packed<'Error#/$defs/Error'>> => {
 	const { endpoint, parameters, user } = request;
 	const { status, code, id } = assertion;
 	const res = await api(endpoint, parameters, user);
diff --git a/packages/misskey-js/src/entities.ts b/packages/misskey-js/src/entities.ts
index 76cae7dda9..44e795ea00 100644
--- a/packages/misskey-js/src/entities.ts
+++ b/packages/misskey-js/src/entities.ts
@@ -7,6 +7,7 @@ type TODO = Record<string, any>;
 
 // NOTE: 極力この型を使うのは避け、UserLite か UserDetailed か明示するように
 export type User = Packed<'User'>;
+
 export type UserLite = Packed<'UserLite'>;
 export type UserDetailed = Packed<'UserDetailed'>;
 export type UserList = Packed<'UserList'>;
diff --git a/packages/misskey-js/src/schemas.ts b/packages/misskey-js/src/schemas.ts
index e51ddb1906..a66ccfb089 100644
--- a/packages/misskey-js/src/schemas.ts
+++ b/packages/misskey-js/src/schemas.ts
@@ -35,6 +35,7 @@ import { packedEmojiDetailedSchema, packedEmojiSimpleSchema } from './schemas/em
 import { packedFlashSchema } from './schemas/flash.js';
 import { packedAdSchema } from './schemas/ad.js';
 import { packedAnnouncementSchema } from './schemas/announcement.js';
+import { Error, ApiError } from './schemas/error.js';
 import type { JSONSchema7, JSONSchema7Definition, GetDef, GetRefs, GetKeys, UnionToArray } from 'schema-type';
 
 export const refs = {
@@ -74,6 +75,9 @@ export const refs = {
 	Flash: packedFlashSchema,
 	Ad: packedAdSchema,
 	Announcement: packedAnnouncementSchema,
+
+	Error: Error,
+	ApiError: ApiError,
 } as const satisfies { [x: string]: JSONSchema7Definition };
 
 export type References = GetRefs<typeof refs>;
diff --git a/packages/misskey-js/src/schemas/blocking.ts b/packages/misskey-js/src/schemas/blocking.ts
index 8c21d1e6f3..f842a489b9 100644
--- a/packages/misskey-js/src/schemas/blocking.ts
+++ b/packages/misskey-js/src/schemas/blocking.ts
@@ -17,6 +17,6 @@ export const packedBlockingSchema = {
 		'id',
 		'createdAt',
 		'blockeeId',
-		'blockee',
+		//'blockee',
 	],
 } as const satisfies JSONSchema7Definition;
diff --git a/packages/misskey-js/src/schemas/error.ts b/packages/misskey-js/src/schemas/error.ts
new file mode 100644
index 0000000000..773713d411
--- /dev/null
+++ b/packages/misskey-js/src/schemas/error.ts
@@ -0,0 +1,34 @@
+import type { JSONSchema7Definition } from 'schema-type';
+
+export const Error = {
+	$id: 'https://misskey-hub.net/api/schemas/Error',
+
+    type: 'object',
+    description: 'An error object.',
+    properties: {
+        code: {
+            type: 'string',
+            description: 'An error code. Unique within the endpoint.',
+        },
+        message: {
+            type: 'string',
+            description: 'An error message.',
+        },
+        id: {
+            type: 'string',
+            format: 'uuid',
+            description: 'An error ID. This ID is static.',
+        },
+    },
+    required: ['code', 'id', 'message'],
+} as const satisfies JSONSchema7Definition;
+
+export const ApiError = {
+	$id: 'https://misskey-hub.net/api/schemas/ApiError',
+
+	type: 'object',
+	properties: {
+		error: { $ref: 'https://misskey-hub.net/api/schemas/Error' },
+	},
+	required: ['error'],
+} as const satisfies JSONSchema7Definition;
diff --git a/packages/misskey-js/test-d/schemas.ts b/packages/misskey-js/test-d/schemas.ts
index af2f5dceb0..c586611d43 100644
--- a/packages/misskey-js/test-d/schemas.ts
+++ b/packages/misskey-js/test-d/schemas.ts
@@ -97,4 +97,8 @@ describe('schemas', () => {
     test('ad', () => {
         type Ad = Packed<'Ad'>;
     });
+    test('error', () => {
+        type Error = Packed<'Error'>;
+        type ApiError = Packed<'ApiError'>;
+    });
 });
diff --git a/packages/misskey-js/test/api.ts b/packages/misskey-js/test/api.ts
index c816608a22..f63c4a96a8 100644
--- a/packages/misskey-js/test/api.ts
+++ b/packages/misskey-js/test/api.ts
@@ -20,7 +20,7 @@ describe('schemas', () => {
 			}
 		});
 
-		test('jointed schema (oneOf)', () => {
+		test('jointed schema', () => {
 			const req = getEndpointSchema('req', key as keyof Endpoints);
 			if (req) ajv.compile(req);
 		});