diff --git a/packages/backend/src/server/api/mastodon/ApiMastodonCompatibleService.ts b/packages/backend/src/server/api/mastodon/ApiMastodonCompatibleService.ts
index df85f21624..e31314e135 100644
--- a/packages/backend/src/server/api/mastodon/ApiMastodonCompatibleService.ts
+++ b/packages/backend/src/server/api/mastodon/ApiMastodonCompatibleService.ts
@@ -18,11 +18,7 @@ export function getClient(
 	const accessTokenArr = authorization?.split(" ") ?? [null];
 	const accessToken = accessTokenArr[accessTokenArr.length - 1];
 	const generator = (megalodon as any).default;
-	const client = generator(
-		"misskey",
-		BASE_URL,
-		accessToken,
-	) as MegalodonInterface;
+       const client = generator(BASE_URL, accessToken) as MegalodonInterface;
 	return client;
 }
 
diff --git a/packages/backend/src/server/api/mastodon/endpoints/account.ts b/packages/backend/src/server/api/mastodon/endpoints/account.ts
index 23d46eea68..c2cbb630a3 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/account.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/account.ts
@@ -42,8 +42,8 @@ export function apiAccountMastodon(router: Router): void {
 			acct.url = `${BASE_URL}/@${acct.url}`;
 			acct.note = acct.note || "";
 			acct.avatar_static = acct.avatar;
-			acct.header = acct.header || "https://http.cat/404";
-			acct.header_static = acct.header || "https://http.cat/404";
+			acct.header = acct.header || "/static-assets/transparent.png";
+			acct.header_static = acct.header || "/static-assets/transparent.png";
 			acct.source = {
 				note: acct.note,
 				fields: acct.fields,
diff --git a/packages/backend/src/server/api/mastodon/endpoints/meta.ts b/packages/backend/src/server/api/mastodon/endpoints/meta.ts
index c68a09585f..8499d62bb2 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/meta.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/meta.ts
@@ -24,7 +24,7 @@ export async function getInstance(response: Entity.Instance) {
 			status_count: await totalStatuses,
 			domain_count: response.stats.domain_count,
 		},
-		thumbnail: response.thumbnail || "https://http.cat/404",
+		thumbnail: response.thumbnail || "/static-assets/transparent.png",
 		languages: meta.langs,
 		registrations: !meta.disableRegistration || response.registrations,
 		approval_required: !response.registrations,
@@ -96,8 +96,8 @@ export async function getInstance(response: Entity.Instance) {
 			url: `${response.uri}/`,
 			avatar: `${response.uri}/static-assets/badges/info.png`,
 			avatar_static: `${response.uri}/static-assets/badges/info.png`,
-			header: "https://http.cat/404",
-			header_static: "https://http.cat/404",
+			header: "/static-assets/transparent.png",
+			header_static: "/static-assets/transparent.png",
 			followers_count: -1,
 			following_count: 0,
 			statuses_count: 0,
diff --git a/packages/backend/src/server/api/mastodon/endpoints/search.ts b/packages/backend/src/server/api/mastodon/endpoints/search.ts
index e1aec3488b..9a07db4dcc 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/search.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/search.ts
@@ -103,7 +103,7 @@ async function getHighlight(
 			i: accessToken,
 		});
 		const data: MisskeyEntity.Note[] = api.data;
-		return data.map((note) => Converter.note(note, domain));
+		return data.map((note) => new Converter(BASE_URL).note(note, domain));
 	} catch (e: any) {
 		console.log(e);
 		console.log(e.response.data);
@@ -131,7 +131,7 @@ async function getFeaturedUser(
 		return data.map((u) => {
 			return {
 				source: "past_interactions",
-				account: Converter.userDetail(u, host),
+				account: new Converter(BASE_URL).userDetail(u, host),
 			};
 		});
 	} catch (e: any) {
diff --git a/packages/backend/src/server/api/mastodon/endpoints/status.ts b/packages/backend/src/server/api/mastodon/endpoints/status.ts
index 86fabb59b8..759faeef96 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/status.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/status.ts
@@ -449,8 +449,8 @@ export function statusModel(
 	const now = new Date().toISOString();
 	return {
 		id: "9atm5frjhb",
-		uri: "https://http.cat/404", // ""
-		url: "https://http.cat/404", // "",
+		uri: "/static-assets/transparent.png", // ""
+		url: "/static-assets/transparent.png", // "",
 		account: {
 			id: "9arzuvv0sw",
 			username: "Reactions",
@@ -462,11 +462,11 @@ export function statusModel(
 			following_count: 0,
 			statuses_count: 0,
 			note: "",
-			url: "https://http.cat/404",
+			url: "/static-assets/transparent.png",
 			avatar: "/static-assets/badges/info.png",
 			avatar_static: "/static-assets/badges/info.png",
-			header: "https://http.cat/404", // ""
-			header_static: "https://http.cat/404", // ""
+			header: "/static-assets/transparent.png", // ""
+			header_static: "/static-assets/transparent.png", // ""
 			emojis: [],
 			fields: [],
 			moved: null,
diff --git a/packages/backend/src/server/index.ts b/packages/backend/src/server/index.ts
index cd2d132199..270a8666de 100644
--- a/packages/backend/src/server/index.ts
+++ b/packages/backend/src/server/index.ts
@@ -166,7 +166,7 @@ mastoRouter.post("/oauth/token", async (ctx) => {
 	let client_id: any = body.client_id;
 	const BASE_URL = `${ctx.request.protocol}://${ctx.request.hostname}`;
 	const generator = (megalodon as any).default;
-	const client = generator("misskey", BASE_URL, null) as MegalodonInterface;
+	const client = generator(BASE_URL, null) as MegalodonInterface;
 	let m = null;
 	let token = null;
 	if (body.code) {