diff --git a/packages/client/src/components/layout/nav.tsx b/packages/client/src/components/layout/nav.tsx
index 5ea962f..bc7b750 100644
--- a/packages/client/src/components/layout/nav.tsx
+++ b/packages/client/src/components/layout/nav.tsx
@@ -63,7 +63,7 @@ export function NavList() {
     const loginInfo = useLogin();
     const navItems = useNavItems();
 
-    return <aside className="h-dvh flex flex-col">
+    return <aside className="h-dvh flex flex-col fixed">
         <nav className="flex flex-col items-center gap-4 px-2 sm:py-5 flex-1">
             {navItems && <>{navItems} <Separator/> </>}
             <NavItem icon={<SearchIcon className="h-5 w-5" />} to="/search" name="Search" />
diff --git a/packages/client/src/hook/useGalleryDoc.ts b/packages/client/src/hook/useGalleryDoc.ts
index 9b24177..71ee319 100644
--- a/packages/client/src/hook/useGalleryDoc.ts
+++ b/packages/client/src/hook/useGalleryDoc.ts
@@ -14,4 +14,8 @@ export function useRehashDoc() {
         });
         mutate(`/api/doc/${id}`);
     };
+}
+
+export function useGalleryDocSimilar(id: string) {
+    return useSWR<Document[]>(`/api/doc/${id}/similars`, fetcher);
 }
\ No newline at end of file
diff --git a/packages/client/src/page/contentInfoPage.tsx b/packages/client/src/page/contentInfoPage.tsx
index 5438dec..adaea0b 100644
--- a/packages/client/src/page/contentInfoPage.tsx
+++ b/packages/client/src/page/contentInfoPage.tsx
@@ -1,11 +1,12 @@
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
-import { useGalleryDoc, useRehashDoc } from "../hook/useGalleryDoc.ts";
+import { useGalleryDoc, useGalleryDocSimilar, useRehashDoc } from "../hook/useGalleryDoc.ts";
 import TagBadge from "@/components/gallery/TagBadge";
 import StyledLink from "@/components/gallery/StyledLink";
 import { Link } from "wouter";
 import { classifyTags } from "../lib/classifyTags.tsx";
 import { DescTagItem, DescItem } from "../components/gallery/DescItem.tsx";
 import { Button } from "@/components/ui/button.tsx";
+import { GalleryCard } from "@/components/gallery/GalleryCard.tsx";
 
 export interface ContentInfoPageProps {
     params: {
@@ -35,7 +36,7 @@ export function ContentInfoPage({ params }: ContentInfoPageProps) {
     const contentLocation = `/doc/${params.id}/reader`;
 
     return (
-        <div className="p-4 h-dvh overflow-auto">
+        <div className="p-4">
             <Link to={contentLocation}>
                 <div className="m-auto h-[400px] mb-4 flex justify-center items-center flex-none bg-[#272733]
             rounded-xl shadow-lg overflow-hidden">
@@ -83,8 +84,40 @@ export function ContentInfoPage({ params }: ContentInfoPageProps) {
                     </div>
                 </CardContent>
             </Card>
+            <SimilarContentCard id={params.id} />
         </div>
     );
 }
 
+function SimilarContentCard({
+    id,
+}: {
+    id: string;
+}){
+    const { data, error, isLoading } = useGalleryDocSimilar(id);
+
+    if (isLoading) {
+        return <div className="p-4">Loading...</div>
+    }
+
+    if (error) {
+        return <div className="p-4">Error: {String(error)}</div>
+    }
+
+    if (!data) {
+        return <div className="p-4">Not found</div>
+    }
+
+    return (
+        <div className="space-y-4 mt-4 mx-2">
+            <h2 className="text-2xl font-bold">Contents with Similar Tags</h2>
+            <div className="grid gap-4 grid-cols-[repeat(auto_fill_300px)]">
+            {data.map((doc) => (
+                <GalleryCard key={doc.id} doc={doc} />
+            ))}
+            </div>
+        </div>
+    )
+}
+
 export default ContentInfoPage;
\ No newline at end of file
diff --git a/packages/client/src/page/galleryPage.tsx b/packages/client/src/page/galleryPage.tsx
index ceb52d2..8dc7b10 100644
--- a/packages/client/src/page/galleryPage.tsx
+++ b/packages/client/src/page/galleryPage.tsx
@@ -65,7 +65,7 @@ export default function Gallery() {
 
 
     const isLoadingMore = data && size > 0 && (data[size - 1] === undefined);
-    return (<div className="p-4 grid gap-2 overflow-auto h-dvh items-start content-start" ref={parentRef}>
+    return (<div className="p-4 grid gap-2 items-start content-start" ref={parentRef}>
         <Search />
         {(word || tags) &&
             <div className="bg-primary rounded-full p-1 sticky top-0 shadow-md z-10">
diff --git a/packages/server/src/database.ts b/packages/server/src/database.ts
index 725d947..88a5063 100644
--- a/packages/server/src/database.ts
+++ b/packages/server/src/database.ts
@@ -1,3 +1,4 @@
+import { Kysely } from "kysely";
 import { getKysely } from "./db/kysely.ts";
 
 export async function connectDB() {
@@ -22,3 +23,22 @@ export async function connectDB() {
 	}
 	return kysely;
 }
+
+async function checkTableExists(kysely: Kysely<any>, table: string) {
+	const result = await kysely.selectFrom("sqlite_master").where("type", "=", "table").where("name", "=", table).executeTakeFirst();
+	return result !== undefined;
+} 
+
+export async function migrateDB() {
+	const kysely = getKysely();
+	let version_number = 0;
+	// is schema_migration exists?
+	const hasTable = await checkTableExists(kysely, "schema_migration");
+	if (!hasTable) {
+		// migrate from 0
+		// create schema_migration
+	}
+
+	const version = await kysely.selectFrom("schema_migration").executeTakeFirst();
+
+}
\ No newline at end of file
diff --git a/packages/server/src/db/doc.ts b/packages/server/src/db/doc.ts
index ec4017c..6249c98 100644
--- a/packages/server/src/db/doc.ts
+++ b/packages/server/src/db/doc.ts
@@ -245,6 +245,41 @@ class SqliteDocumentAccessor implements DocumentAccessor {
 		c.tags.splice(c.tags.indexOf(tag_name), 1);
 		return true;
 	}
+
+	async getSimilarDocument(doc: Document): Promise<Document[]> {
+		const tags = doc.tags.filter((x) => !x.startsWith("type:")
+			&& x !== "series:original");
+		if (tags.length === 0) return [];
+		// get similar document based on tags count.
+		const results = await this.kysely
+			.selectFrom("document as doc")
+			.innerJoin("doc_tag_relation", "doc_tag_relation.doc_id", "doc.id")
+			.where("doc_tag_relation.tag_name", "in", tags)
+			.where("doc.id", "<>", doc.id)
+			.selectAll()
+			.select(qb => ([
+				qb.fn.count("doc_tag_relation.tag_name").as("tag_count"),
+
+				qb.selectFrom(e =>
+					e.selectFrom("doc_tag_relation")
+						.select(["doc_tag_relation.tag_name"])
+						.whereRef("doc.id", "=", "doc_tag_relation.doc_id")
+						.as("agg")
+				).select(e => e.fn.agg<string>("json_group_array", ["agg.tag_name"])
+					.as("tags_list")
+				).as("tags")
+			]))
+			.groupBy("doc.id")
+			.orderBy("tag_count", "desc")
+			.limit(10)
+			.execute();
+		// TODO: tf-idf or other similarity calculation
+		return results.map((x) => ({
+			...x,
+			tags: JSON.parse(x.tags ?? "[]"),
+			additional: {},
+		}));
+	}
 }
 export const createSqliteDocumentAccessor = (kysely = getKysely()): DocumentAccessor => {
 	return new SqliteDocumentAccessor(kysely);
diff --git a/packages/server/src/model/doc.ts b/packages/server/src/model/doc.ts
index 34654ef..dd9abab 100644
--- a/packages/server/src/model/doc.ts
+++ b/packages/server/src/model/doc.ts
@@ -85,4 +85,9 @@ export interface DocumentAccessor {
 	 * @returns if success, return true
 	 */
 	delTag: (c: Document, tag_name: string) => Promise<boolean>;
+	/**
+	 * get similar document
+	 * @returns similar document list
+	 */
+	getSimilarDocument: (c: Document) => Promise<Document[]>;
 }
diff --git a/packages/server/src/route/all.ts b/packages/server/src/route/all.ts
index 5659017..34fbd09 100644
--- a/packages/server/src/route/all.ts
+++ b/packages/server/src/route/all.ts
@@ -16,6 +16,11 @@ const all_middleware =
 			ctx.status = 404;
 			return;
 		}
+		if (ctx.state.location === undefined) {
+			ctx.status = 404;
+			return;
+		}
+		
 		if (ctx.state.location.type !== cont) {
 			console.error("not matched");
 			ctx.status = 404;
diff --git a/packages/server/src/route/contents.ts b/packages/server/src/route/contents.ts
index 811b6b8..03f5296 100644
--- a/packages/server/src/route/contents.ts
+++ b/packages/server/src/route/contents.ts
@@ -184,18 +184,31 @@ function RehashContentHandler(controller: DocumentAccessor) {
 	};
 }
 
+function getSimilarDocumentHandler(controller: DocumentAccessor) {
+	return async (ctx: Context, next: Next) => {
+		const num = Number.parseInt(ctx.params.num);
+		const c = await controller.findById(num, true);
+		if (c === undefined) {
+			return sendError(404);
+		}
+		const r = await controller.getSimilarDocument(c);
+		ctx.body = r;
+		ctx.type = "json";
+	};
+}
+
 export const getContentRouter = (controller: DocumentAccessor) => {
 	const ret = new Router();
 	ret.get("/search", PerCheck(Per.QueryContent), ContentQueryHandler(controller));
 	ret.get("/:num(\\d+)", PerCheck(Per.QueryContent), ContentIDHandler(controller));
+	ret.all("/:num(\\d+)/(.*)", PerCheck(Per.QueryContent), ContentHandler(controller));
 	ret.post("/:num(\\d+)", AdminOnly, UpdateContentHandler(controller));
-	// ret.use("/:num(\\d+)/:content_type");
+	ret.del("/:num(\\d+)", AdminOnly, DeleteContentHandler(controller));
 	// ret.post("/",AdminOnly,CreateContentHandler(controller));
+	ret.get("/:num(\\d+)/similars", PerCheck(Per.QueryContent), getSimilarDocumentHandler(controller));
 	ret.get("/:num(\\d+)/tags", PerCheck(Per.QueryContent), ContentTagIDHandler(controller));
 	ret.post("/:num(\\d+)/tags/:tag", PerCheck(Per.ModifyTag), AddTagHandler(controller));
 	ret.del("/:num(\\d+)/tags/:tag", PerCheck(Per.ModifyTag), DelTagHandler(controller));
-	ret.del("/:num(\\d+)", AdminOnly, DeleteContentHandler(controller));
-	ret.all("/:num(\\d+)/(.*)", PerCheck(Per.QueryContent), ContentHandler(controller));
 	ret.use("/:num(\\d+)", PerCheck(Per.QueryContent), new AllContentRouter().routes());
 	ret.post("/:num(\\d+)/_rehash", AdminOnly, RehashContentHandler(controller));
 	return ret;
diff --git a/packages/server/src/server.ts b/packages/server/src/server.ts
index f7b6e34..e9f2e49 100644
--- a/packages/server/src/server.ts
+++ b/packages/server/src/server.ts
@@ -236,9 +236,10 @@ class ServerApplication {
 		return this.app.listen(setting.port, setting.localmode ? "127.0.0.1" : "0.0.0.0");
 	}
 	static async createServer() {
-		const setting = get_setting();
 		const db = await connectDB();
 
+		// todo : db migration
+
 		const app = new ServerApplication({
 			userController: createSqliteUserController(db),
 			documentController: createSqliteDocumentAccessor(db),