diff --git a/src/main/java/com/example/jerseyexercise/resources/FishRest.java b/src/main/java/com/example/jerseyexercise/resources/FishRest.java
new file mode 100644
index 0000000..364548f
--- /dev/null
+++ b/src/main/java/com/example/jerseyexercise/resources/FishRest.java
@@ -0,0 +1,47 @@
+package com.example.jerseyexercise.resources;
+
+import jakarta.ws.rs.*;
+import jakarta.ws.rs.core.MediaType;
+import org.springframework.stereotype.Component;
+
+import java.util.HashMap;
+import java.util.Set;
+
+// get: /monaka -> 全アカウントのid一覧を返す
+// post(id, name): /monaka -> 新規アカウント登録
+
+// get: /monaka/{id} -> idで指定したアカウントの名前を返す
+// put(name): /monaka/{id} -> idで指定したアカウントの名前をnameに変更する
+
+@Path("/fish")
+@Component
+public class FishRest {
+    private HashMap<String, String> accounts = new HashMap<>();
+
+    @GET
+    @Produces(MediaType.APPLICATION_JSON)
+    public Set<String> getAccounts() {
+        return accounts.keySet();
+    }
+
+    @POST
+    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
+    public void signup(@FormParam("id") String id, @FormParam("name") String name) {
+        accounts.put(id, name);
+    }
+
+    @Path("/{id}")
+    @GET
+    @Produces(MediaType.TEXT_PLAIN)
+    public String getName(@PathParam("id") String id) {
+        return accounts.get(id);
+    }
+
+    @Path("/{id}")
+    @PUT
+    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
+    public void setName(@PathParam("id") String id, @FormParam("name") String name) {
+        if (accounts.get(id) == null) return;
+        accounts.put(id, name);
+    }
+}