diff --git a/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/down.cql b/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/down.cql
index cc1f948761..5d48bbcc0d 100644
--- a/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/down.cql
+++ b/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/down.cql
@@ -9,6 +9,7 @@ DROP MATERIALIZED VIEW IF EXISTS global_timeline;
 DROP MATERIALIZED VIEW IF EXISTS note_by_renote_id_and_user_id;
 DROP MATERIALIZED VIEW IF EXISTS note_by_renote_id;
 DROP MATERIALIZED VIEW IF EXISTS note_by_user_id;
+DROP INDEX IF EXISTS note_by_reply_id;
 DROP INDEX IF EXISTS note_by_id;
 DROP INDEX IF EXISTS note_by_uri;
 DROP INDEX IF EXISTS note_by_url;
diff --git a/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/up.cql b/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/up.cql
index 080a85cba4..50c952e6ec 100644
--- a/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/up.cql
+++ b/packages/backend/native-utils/scylla-migration/cql/1689400417034_timeline/up.cql
@@ -75,6 +75,7 @@ CREATE TABLE IF NOT EXISTS note ( -- Store all posts
 CREATE INDEX IF NOT EXISTS note_by_uri ON note ("uri");
 CREATE INDEX IF NOT EXISTS note_by_url ON note ("url");
 CREATE INDEX IF NOT EXISTS note_by_id ON note ("id");
+CREATE INDEX IF NOT EXISTS note_by_reply_id ON note ("replyId");
 
 CREATE MATERIALIZED VIEW IF NOT EXISTS note_by_user_id AS
 	SELECT * FROM note
diff --git a/packages/backend/src/db/cql.ts b/packages/backend/src/db/cql.ts
index 366c5a6dc2..c807e322d7 100644
--- a/packages/backend/src/db/cql.ts
+++ b/packages/backend/src/db/cql.ts
@@ -48,6 +48,7 @@ export const scyllaQueries = {
 			byId: `SELECT * FROM note WHERE "id" = ?`,
 			byUserId: `SELECT * FROM note_by_user_id WHERE "userId" IN ?`,
 			byRenoteId: `SELECT * FROM note_by_renote_id WHERE "renoteId" = ?`,
+			byReplyId: `SELECT * FROM note_by_reply_id WHERE "replyId" = ?`
 		},
 		delete: `DELETE FROM note WHERE "createdAtDate" = ? AND "createdAt" = ? AND "userId" = ? AND "userHost" = ? AND "visibility" = ?`,
 		update: {
diff --git a/packages/backend/src/db/scylla.ts b/packages/backend/src/db/scylla.ts
index 76b09b0156..0cfd098cd3 100644
--- a/packages/backend/src/db/scylla.ts
+++ b/packages/backend/src/db/scylla.ts
@@ -82,6 +82,24 @@ export interface ScyllaDriveFile {
 	height: number | null;
 }
 
+export function getScyllaDrivePublicUrl(file: ScyllaDriveFile, thumbnail = false): string | null {
+	const isImage =
+		file.type &&
+		[
+			"image/png",
+			"image/apng",
+			"image/gif",
+			"image/jpeg",
+			"image/webp",
+			"image/svg+xml",
+			"image/avif",
+		].includes(file.type);
+
+	return thumbnail
+		? file.thumbnailUrl || (isImage ? file.url : null)
+		: file.url;
+}
+
 export interface ScyllaNoteEditHistory {
 	content: string;
 	cw: string;
diff --git a/packages/backend/src/models/repositories/drive-file.ts b/packages/backend/src/models/repositories/drive-file.ts
index 3918f7947b..9c319e2a49 100644
--- a/packages/backend/src/models/repositories/drive-file.ts
+++ b/packages/backend/src/models/repositories/drive-file.ts
@@ -10,6 +10,7 @@ import { Meta } from "@/models/entities/meta.js";
 import { fetchMeta } from "@/misc/fetch-meta.js";
 import { Users, DriveFolders } from "../index.js";
 import { deepClone } from "@/misc/clone.js";
+import { ScyllaDriveFile } from "@/db/scylla.js";
 
 type PackOptions = {
 	detail?: boolean;
diff --git a/packages/backend/src/models/repositories/note.ts b/packages/backend/src/models/repositories/note.ts
index 1aef1cdef9..5e8b5ca480 100644
--- a/packages/backend/src/models/repositories/note.ts
+++ b/packages/backend/src/models/repositories/note.ts
@@ -33,6 +33,7 @@ import {
 	prepared,
 	scyllaClient,
 	parseScyllaReaction,
+	getScyllaDrivePublicUrl,
 } from "@/db/scylla.js";
 import { LocalFollowingsCache } from "@/misc/cache.js";
 import { userByIdCache } from "@/services/user-cache.js";
@@ -280,6 +281,7 @@ export const NoteRepository = db.getRepository(Note).extend({
 			files: scyllaClient
 				? (note as ScyllaNote).files.map((file) => ({
 						...file,
+						thumbnailUrl: getScyllaDrivePublicUrl(file, true),
 						createdAt: file.createdAt.toISOString(),
 						properties: {
 							width: file.width ?? undefined,
diff --git a/packages/backend/src/server/api/endpoints/notes/children.ts b/packages/backend/src/server/api/endpoints/notes/children.ts
index a35b17a022..1c1a496f41 100644
--- a/packages/backend/src/server/api/endpoints/notes/children.ts
+++ b/packages/backend/src/server/api/endpoints/notes/children.ts
@@ -4,6 +4,9 @@ import { makePaginationQuery } from "../../common/make-pagination-query.js";
 import { generateVisibilityQuery } from "../../common/generate-visibility-query.js";
 import { generateMutedUserQuery } from "../../common/generate-muted-user-query.js";
 import { generateBlockedUserQuery } from "../../common/generate-block-query.js";
+import { parseScyllaNote, prepared, scyllaClient } from "@/db/scylla.js";
+import { getNote } from "@/server/api/common/getters.js";
+import type { Note } from "@/models/entities/note.js";
 
 export const meta = {
 	tags: ["notes"],
@@ -38,18 +41,52 @@ export const paramDef = {
 } as const;
 
 export default define(meta, paramDef, async (ps, user) => {
+	if (scyllaClient) {
+		const root = await getNote(ps.noteId, user).catch(() => null);
+		if (!root) {
+			return await Notes.packMany([]);
+		}
+
+		// Find replies in BFS manner
+		const queue = [root];
+		const foundReplies: Note[] = [];
+		let depth = 0;
+
+		while (
+			queue.length > 0 &&
+			foundReplies.length < ps.limit &&
+			depth < ps.depth
+		) {
+			const note = queue.shift();
+			if (note) {
+				const result = await scyllaClient.execute(
+					prepared.note.select.byReplyId,
+					[note.id],
+					{ prepare: true },
+				);
+				if (result.rowLength > 0) {
+					const replies = result.rows.map(parseScyllaNote);
+					foundReplies.push(...replies);
+					queue.push(...replies);
+					depth++;
+				}
+			}
+		}
+
+		return await Notes.packMany(foundReplies.slice(0, ps.limit), user, {
+			detail: false,
+			scyllaNote: true,
+		});
+	}
+
 	const query = makePaginationQuery(
 		Notes.createQueryBuilder("note"),
 		ps.sinceId,
 		ps.untilId,
-	)
-		.andWhere(
-			"note.id IN (SELECT id FROM note_replies(:noteId, :depth, :limit))",
-			{ noteId: ps.noteId, depth: ps.depth, limit: ps.limit },
-		)
-		.innerJoinAndSelect("note.user", "user")
-		.leftJoinAndSelect("user.avatar", "avatar")
-		.leftJoinAndSelect("user.banner", "banner");
+	).andWhere(
+		"note.id IN (SELECT id FROM note_replies(:noteId, :depth, :limit))",
+		{ noteId: ps.noteId, depth: ps.depth, limit: ps.limit },
+	);
 
 	generateVisibilityQuery(query, user);
 	if (user) {
diff --git a/packages/backend/src/services/note/delete.ts b/packages/backend/src/services/note/delete.ts
index 563b1fb887..9813ef9c15 100644
--- a/packages/backend/src/services/note/delete.ts
+++ b/packages/backend/src/services/note/delete.ts
@@ -148,7 +148,7 @@ export default async function (
 			deletedAt: deletedAt,
 		});
 
-		//#region ローカルの投稿なら削除アクティビティを配送
+		//#region Deliver Delete activity if it's from a local account
 		if (Users.isLocalUser(user) && !note.localOnly) {
 			let renote: Note | null = null;
 
@@ -159,9 +159,18 @@ export default async function (
 				!note.hasPoll &&
 				(note.fileIds == null || note.fileIds.length === 0)
 			) {
-				renote = await Notes.findOneBy({
-					id: note.renoteId,
-				});
+				if (scyllaClient) {
+					const result = await scyllaClient.execute(
+						prepared.note.select.byId,
+						[note.renoteId],
+						{ prepare: true },
+					);
+					if (result.rowLength > 0) renote = parseScyllaNote(result.first());
+				} else {
+					renote = await Notes.findOneBy({
+						id: note.renoteId,
+					});
+				}
 			}
 
 			const content = renderActivity(
@@ -249,18 +258,42 @@ async function findCascadingNotes(note: Note) {
 	const cascadingNotes: Note[] = [];
 
 	const recursive = async (noteId: string) => {
-		const query = Notes.createQueryBuilder("note")
-			.where("note.replyId = :noteId", { noteId })
-			.orWhere(
-				new Brackets((q) => {
-					q.where("note.renoteId = :noteId", { noteId }).andWhere(
-						"note.text IS NOT NULL",
-					);
-				}),
-			)
-			.leftJoinAndSelect("note.user", "user");
-		const replies = await query.getMany();
-		for (const reply of replies) {
+		let notes: Note[] = [];
+
+		if (scyllaClient) {
+			const replies = await scyllaClient.execute(
+				prepared.note.select.byReplyId,
+				[noteId],
+				{ prepare: true },
+			);
+			if (replies.rowLength > 0) {
+				notes.push(...replies.rows.map(parseScyllaNote));
+			}
+			const renotes = await scyllaClient.execute(
+				prepared.note.select.byRenoteId,
+				[noteId],
+				{ prepare: true },
+			);
+			if (renotes.rowLength > 0) {
+				notes.push(
+					...renotes.rows.map(parseScyllaNote).filter((note) => !!note.text),
+				);
+			}
+		} else {
+			const query = Notes.createQueryBuilder("note")
+				.where("note.replyId = :noteId", { noteId })
+				.orWhere(
+					new Brackets((q) => {
+						q.where("note.renoteId = :noteId", { noteId }).andWhere(
+							"note.text IS NOT NULL",
+						);
+					}),
+				)
+				.leftJoinAndSelect("note.user", "user");
+			notes = await query.getMany();
+		}
+
+		for (const reply of notes) {
 			cascadingNotes.push(reply);
 			await recursive(reply.id);
 		}