diff --git a/src/main/java/com/cake/pop/domain/letter/controller/LetterController.java b/src/main/java/com/cake/pop/domain/letter/controller/LetterController.java
index 04ec3d9..dbb4e90 100644
--- a/src/main/java/com/cake/pop/domain/letter/controller/LetterController.java
+++ b/src/main/java/com/cake/pop/domain/letter/controller/LetterController.java
@@ -1,6 +1,7 @@
 package com.cake.pop.domain.letter.controller;
 
 import com.cake.pop.domain.letter.dto.request.CreateLetterRequest;
+import com.cake.pop.domain.letter.dto.request.CreateStorageRequest;
 import com.cake.pop.domain.letter.dto.response.GetLetterResponse;
 import com.cake.pop.domain.letter.dto.response.GetLettersResponse;
 import com.cake.pop.domain.letter.service.LetterService;
@@ -24,7 +25,7 @@ public class LetterController {
 
     @PostMapping
     public ResponseEntity<Void> createLetter(@RequestBody @Valid CreateLetterRequest request) {
-        letterService.create(request);
+        letterService.createLetter(request);
         return ResponseEntity.ok().build();
     }
 
@@ -39,4 +40,13 @@ public ResponseEntity<GetLetterResponse> getLetter(@PathVariable("letterId") Lon
         GetLetterResponse response = letterService.getLetter(letterId);
         return ResponseEntity.ok(response);
     }
+
+    @PostMapping("/storage")
+    public ResponseEntity<Void> createStorage(@RequestBody @Valid CreateStorageRequest request){
+        Long userId = 1L;
+        letterService.createStorage(userId, request);
+        return ResponseEntity.ok().build();
+    }
+
+
 }
diff --git a/src/main/java/com/cake/pop/domain/letter/dto/request/CreateStorageRequest.java b/src/main/java/com/cake/pop/domain/letter/dto/request/CreateStorageRequest.java
new file mode 100644
index 0000000..da0c3d2
--- /dev/null
+++ b/src/main/java/com/cake/pop/domain/letter/dto/request/CreateStorageRequest.java
@@ -0,0 +1,6 @@
+package com.cake.pop.domain.letter.dto.request;
+
+public record CreateStorageRequest(
+        Long letterId
+) {
+}
diff --git a/src/main/java/com/cake/pop/domain/letter/dto/response/GetLetterResponse.java b/src/main/java/com/cake/pop/domain/letter/dto/response/GetLetterResponse.java
index 3f13010..4160f1d 100644
--- a/src/main/java/com/cake/pop/domain/letter/dto/response/GetLetterResponse.java
+++ b/src/main/java/com/cake/pop/domain/letter/dto/response/GetLetterResponse.java
@@ -3,6 +3,7 @@
 public record GetLetterResponse(
         Long letterId,
         String content,
-        String imageUrl
+        String imageUrl,
+        String region
 ) {
 }
diff --git a/src/main/java/com/cake/pop/domain/letter/repository/LetterRepository.java b/src/main/java/com/cake/pop/domain/letter/repository/LetterRepository.java
index df42be6..79af9d4 100644
--- a/src/main/java/com/cake/pop/domain/letter/repository/LetterRepository.java
+++ b/src/main/java/com/cake/pop/domain/letter/repository/LetterRepository.java
@@ -5,7 +5,10 @@
 import com.cake.pop.entity.Mailbox;
 import com.cake.pop.global.exception.RestApiException;
 import java.util.List;
+import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
 @Repository
@@ -13,7 +16,15 @@ public interface LetterRepository extends JpaRepository<Letter, Long> {
 
     List<Letter> findByMailbox(Mailbox mailbox);
 
+    @Query("SELECT l FROM Letter l JOIN FETCH l.mailbox WHERE l.id = :id")
+    Optional<Letter> findByIdWithMailbox(@Param("id") Long id);
+
     default Letter getById(Long id) {
         return findById(id).orElseThrow(() -> new RestApiException(LetterErrorCode.LETTER_NOT_FOUND));
     }
+
+    default Letter getByIdWithMailbox(Long id) {
+        return findByIdWithMailbox(id)
+                .orElseThrow(() -> new RestApiException(LetterErrorCode.LETTER_NOT_FOUND));
+    }
 }
diff --git a/src/main/java/com/cake/pop/domain/letter/repository/StorageRepository.java b/src/main/java/com/cake/pop/domain/letter/repository/StorageRepository.java
new file mode 100644
index 0000000..00a4ad7
--- /dev/null
+++ b/src/main/java/com/cake/pop/domain/letter/repository/StorageRepository.java
@@ -0,0 +1,9 @@
+package com.cake.pop.domain.letter.repository;
+
+import com.cake.pop.entity.Storage;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface StorageRepository extends JpaRepository<Storage, Long> {
+}
diff --git a/src/main/java/com/cake/pop/domain/letter/service/LetterService.java b/src/main/java/com/cake/pop/domain/letter/service/LetterService.java
index 3b5aebf..8b0d9ad 100644
--- a/src/main/java/com/cake/pop/domain/letter/service/LetterService.java
+++ b/src/main/java/com/cake/pop/domain/letter/service/LetterService.java
@@ -1,13 +1,18 @@
 package com.cake.pop.domain.letter.service;
 
 import com.cake.pop.domain.letter.dto.request.CreateLetterRequest;
+import com.cake.pop.domain.letter.dto.request.CreateStorageRequest;
 import com.cake.pop.domain.letter.dto.response.GetLetterResponse;
 import com.cake.pop.domain.letter.dto.response.GetLettersResponse;
 import com.cake.pop.domain.letter.dto.response.SimpleLetterDto;
 import com.cake.pop.domain.letter.repository.LetterRepository;
 import com.cake.pop.domain.letter.repository.MailboxRepository;
+import com.cake.pop.domain.letter.repository.StorageRepository;
+import com.cake.pop.domain.user.repository.UserRepository;
 import com.cake.pop.entity.Letter;
 import com.cake.pop.entity.Mailbox;
+import com.cake.pop.entity.Storage;
+import com.cake.pop.entity.User;
 import com.cake.pop.entity.enums.Region;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
@@ -19,11 +24,16 @@ public class LetterService {
 
     private final LetterRepository letterRepository;
     private final MailboxRepository mailboxRepository;
+    private final StorageRepository storageRepository;
+    private final UserRepository userRepository;
 
-    public void create(CreateLetterRequest request) {
+    public void createLetter(CreateLetterRequest request) {
         Mailbox findMailbox = mailboxRepository.getFirstByRegion(request.region());
+        findMailbox.increaseLetterCount();
+
         Letter letter = Letter.of(request.content(), findMailbox, request.imageUrl());
         letterRepository.save(letter);
+        mailboxRepository.save(findMailbox);
     }
 
     public GetLettersResponse getLetters(String region){
@@ -43,12 +53,21 @@ public GetLettersResponse getLetters(String region){
     }
 
     public GetLetterResponse getLetter(Long letterId){
-        Letter findLetter = letterRepository.getById(letterId);
+        Letter findLetter = letterRepository.getByIdWithMailbox(letterId);
 
         return new GetLetterResponse(
                 findLetter.getId(),
                 findLetter.getContent(),
-                findLetter.getImageUrl()
+                findLetter.getImageUrl(),
+                findLetter.getMailbox().getRegion().getName()
         );
     }
+
+    public void createStorage(Long userId, CreateStorageRequest request){
+        User findUser = userRepository.getById(userId);
+        Letter findLetter = letterRepository.getById(request.letterId());
+        Storage storage = Storage.of(findUser, findLetter);
+
+        storageRepository.save(storage);
+    }
 }
diff --git a/src/main/java/com/cake/pop/entity/Mailbox.java b/src/main/java/com/cake/pop/entity/Mailbox.java
index 489c713..7d9e3d2 100644
--- a/src/main/java/com/cake/pop/entity/Mailbox.java
+++ b/src/main/java/com/cake/pop/entity/Mailbox.java
@@ -44,4 +44,8 @@ public static Mailbox of(Region region) {
                 .region(region)
                 .build();
     }
+
+    public void increaseLetterCount() {
+        this.letterCount = this.letterCount + 1;
+    }
 }