diff --git a/packages/backend/migration/1740129169650-system-accounts-2.js b/packages/backend/migration/1740129169650-system-accounts-2.js
index 07270855b..c03f0337a 100644
--- a/packages/backend/migration/1740129169650-system-accounts-2.js
+++ b/packages/backend/migration/1740129169650-system-accounts-2.js
@@ -13,6 +13,10 @@ export class SystemAccounts21740129169650 {
 
     async down(queryRunner) {
         await queryRunner.query(`ALTER TABLE "meta" ADD "proxyAccountId" character varying(32)`);
+        const proxyAccountId = await queryRunner.query(`SELECT "userId" FROM "system_account" WHERE "type" = 'proxy' ORDER BY "id" DESC LIMIT 1`);
+        if (proxyAccountId && proxyAccountId.length >= 1) {
+            await queryRunner.query(`UPDATE "meta" SET "proxyAccountId" = '${proxyAccountId[0].userId}'`);
+        }
         await queryRunner.query(`ALTER TABLE "meta" ADD CONSTRAINT "FK_ab1bc0c1e209daa77b8e8d212ad" FOREIGN KEY ("proxyAccountId") REFERENCES "user"("id") ON DELETE SET NULL ON UPDATE NO ACTION`);
     }
 }
diff --git a/packages/backend/migration/1740133121105-system-accounts-3.js b/packages/backend/migration/1740133121105-system-accounts-3.js
index 02f9207cd..a1f8c996f 100644
--- a/packages/backend/migration/1740133121105-system-accounts-3.js
+++ b/packages/backend/migration/1740133121105-system-accounts-3.js
@@ -10,10 +10,10 @@ export class SystemAccounts31740133121105 {
         await queryRunner.query(`ALTER TABLE "meta" ADD "rootUserId" character varying(32)`);
         await queryRunner.query(`ALTER TABLE "meta" ADD CONSTRAINT "FK_c80e4079d632f95eac06a9d28cc" FOREIGN KEY ("rootUserId") REFERENCES "user"("id") ON DELETE SET NULL ON UPDATE NO ACTION`);
 
-				const users = await queryRunner.query(`SELECT "id" FROM "user" WHERE "isRoot" = true LIMIT 1`);
-				if (users.length > 0) {
-					await queryRunner.query(`UPDATE "meta" SET "rootUserId" = $1`, [users[0].id]);
-				}
+        const users = await queryRunner.query(`SELECT "id" FROM "user" WHERE "isRoot" = true LIMIT 1`);
+        if (users.length > 0) {
+            await queryRunner.query(`UPDATE "meta" SET "rootUserId" = $1`, [users[0].id]);
+        }
     }
 
     async down(queryRunner) {
diff --git a/packages/backend/migration/1740993126937-system-accounts-4.js b/packages/backend/migration/1740993126937-system-accounts-4.js
new file mode 100644
index 000000000..83654aca8
--- /dev/null
+++ b/packages/backend/migration/1740993126937-system-accounts-4.js
@@ -0,0 +1,17 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export class SystemAccounts41740993126937 {
+    name = 'SystemAccounts41740993126937'
+
+    async up(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "user" DROP COLUMN "isRoot"`);
+    }
+
+    async down(queryRunner) {
+        // down 実行時は isRoot = true のユーザーが存在しなくなるため手動で対応する必要あり
+        await queryRunner.query(`ALTER TABLE "user" ADD "isRoot" boolean NOT NULL DEFAULT false`);
+    }
+}