diff --git a/packages/backend/src/core/UtilityService.ts b/packages/backend/src/core/UtilityService.ts
index 24ded0677d..7e0321f797 100644
--- a/packages/backend/src/core/UtilityService.ts
+++ b/packages/backend/src/core/UtilityService.ts
@@ -131,6 +131,12 @@ export class UtilityService {
 			return mastoHost[1];
 		}
 
+		// XServer SNS
+		const xserverSns = hostname.match(/\.?([a-zA-Z0-9-]+\.xsns\.jp)$/i);
+		if (xserverSns) {
+			return xserverSns[1];
+		}
+
 		return null;
 	}
 
diff --git a/packages/backend/test/unit/UtilityService.ts b/packages/backend/test/unit/UtilityService.ts
index d86e794f2f..27f22de917 100644
--- a/packages/backend/test/unit/UtilityService.ts
+++ b/packages/backend/test/unit/UtilityService.ts
@@ -38,6 +38,8 @@ describe('UtilityService', () => {
 		test('special', () => {
 			assert.equal(utilityService.punyHostPSLDomain('http://foo.masto.host'), 'foo.masto.host');
 			assert.equal(utilityService.punyHostPSLDomain('http://foo.bar.masto.host'), 'bar.masto.host');
+			assert.equal(utilityService.punyHostPSLDomain('http://foo.xsns.jp'), 'foo.xsns.jp');
+			assert.equal(utilityService.punyHostPSLDomain('http://foo.bar.xsns.jp'), 'bar.xsns.jp');
 		});
 	});
 });