diff --git a/spring-data-jpa-2/initial/src/main/java/cholog/Author.java b/spring-data-jpa-2/initial/src/main/java/cholog/Author.java
index 937debe1..d7f26ba7 100644
--- a/spring-data-jpa-2/initial/src/main/java/cholog/Author.java
+++ b/spring-data-jpa-2/initial/src/main/java/cholog/Author.java
@@ -1,17 +1,23 @@
 package cholog;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
+
+import java.util.HashSet;
+import java.util.Set;
 
 @Entity
 public class Author {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
+    @OneToOne
+    Person person;
+
+    @OneToMany(mappedBy = "author")
+    Set<BookAuthor> books = new HashSet<>();
 
     public Author(Person person) {
+        this.person = person;
     }
 
     public Author() {
@@ -22,6 +28,10 @@ public Long getId() {
     }
 
     public Person getPerson() {
-        return null;
+        return person;
+    }
+
+    public Set<BookAuthor> getBooks() {
+        return books;
     }
 }
diff --git a/spring-data-jpa-2/initial/src/main/java/cholog/Book.java b/spring-data-jpa-2/initial/src/main/java/cholog/Book.java
index 6f119218..ba1d00cb 100644
--- a/spring-data-jpa-2/initial/src/main/java/cholog/Book.java
+++ b/spring-data-jpa-2/initial/src/main/java/cholog/Book.java
@@ -1,10 +1,8 @@
 package cholog;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 
+import java.util.HashSet;
 import java.util.Set;
 
 @Entity
@@ -13,12 +11,19 @@ public class Book {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
     private String name;
+    @ManyToOne
+    Publisher publisher;
+
+    @OneToMany(mappedBy = "book")
+    Set<BookAuthor> authors = new HashSet<>();
 
     public Book() {
 
     }
 
     public Book(String name, Publisher publisher) {
+        this.name = name;
+        this.publisher = publisher;
     }
 
     public Long getId() {
@@ -30,10 +35,10 @@ public String getName() {
     }
 
     public Publisher getPublisher() {
-        return null;
+        return publisher;
     }
 
-    public Set<Author> getAuthors() {
-        return null;
+    public Set<BookAuthor> getAuthors() {
+        return authors;
     }
 }
diff --git a/spring-data-jpa-2/initial/src/main/java/cholog/BookAuthor.java b/spring-data-jpa-2/initial/src/main/java/cholog/BookAuthor.java
index 4d9c8d73..e2d1df45 100644
--- a/spring-data-jpa-2/initial/src/main/java/cholog/BookAuthor.java
+++ b/spring-data-jpa-2/initial/src/main/java/cholog/BookAuthor.java
@@ -1,7 +1,26 @@
 package cholog;
 
+import jakarta.persistence.*;
+
+@Entity
 public class BookAuthor {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne
+    Book book;
+
+    @ManyToOne
+    Author author;
+
     public BookAuthor(Book book, Author author) {
+        this.book = book;
+        this.author = author;
+    }
+
+    public BookAuthor() {
 
     }
 }
diff --git a/spring-data-jpa-2/initial/src/main/java/cholog/Person.java b/spring-data-jpa-2/initial/src/main/java/cholog/Person.java
index 6cf1d009..3dd4ef38 100644
--- a/spring-data-jpa-2/initial/src/main/java/cholog/Person.java
+++ b/spring-data-jpa-2/initial/src/main/java/cholog/Person.java
@@ -1,9 +1,6 @@
 package cholog;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 
 @Entity
 public class Person {
@@ -11,7 +8,8 @@ public class Person {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
     private String name;
-
+    @OneToOne(mappedBy = "person", fetch = FetchType.LAZY)
+    Author author;
     public Person() {
 
     }
@@ -29,6 +27,6 @@ public String getName() {
     }
 
     public Author getAuthor() {
-        return null;
+        return author;
     }
 }
diff --git a/spring-data-jpa-2/initial/src/main/java/cholog/Publisher.java b/spring-data-jpa-2/initial/src/main/java/cholog/Publisher.java
index b0c6303e..60e1b6bb 100644
--- a/spring-data-jpa-2/initial/src/main/java/cholog/Publisher.java
+++ b/spring-data-jpa-2/initial/src/main/java/cholog/Publisher.java
@@ -1,10 +1,8 @@
 package cholog;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
 
+import java.util.HashSet;
 import java.util.Set;
 
 @Entity
@@ -13,6 +11,8 @@ public class Publisher {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
     private String name;
+    @OneToMany(mappedBy = "publisher", fetch = FetchType.EAGER)
+    Set<Book> books = new HashSet<>();
 
     public Publisher(String name) {
         this.name = name;
@@ -30,10 +30,10 @@ public String getName() {
     }
 
     public void addBook(Book book) {
-
+        books.add(book);
     }
 
     public Set<Book> getBooks() {
-        return null;
+        return books;
     }
 }
diff --git a/spring-data-jpa-2/initial/src/test/java/cholog/ManyToOneTest.java b/spring-data-jpa-2/initial/src/test/java/cholog/ManyToOneTest.java
index 71ef6b8f..bf5a20c6 100644
--- a/spring-data-jpa-2/initial/src/test/java/cholog/ManyToOneTest.java
+++ b/spring-data-jpa-2/initial/src/test/java/cholog/ManyToOneTest.java
@@ -45,8 +45,8 @@ void biDirection() {
         entityManager.persist(book);
         publisher.addBook(book);
 
-        entityManager.flush();
-        entityManager.clear();
+        entityManager.flush(); // 영속성 컨텍스트에 있는 publisher와 book 엔티티의 상태(추가 및 연관관계 설정)가 데이터베이스에 반영됩니다. 즉, Publisher와 Book 객체가 실제 데이터베이스에 저장
+        entityManager.clear(); // 영속성 컨텍스트를 초기화하여 현재 관리되고 있는 모든 엔티티를 비영속 상태로 만듭니다. 이후 Publisher 객체를 조회할 때, 영속성 컨텍스트가 아닌 데이터베이스에서 해당 엔티티를 다시 가져오게 됩니다
 
         Publisher persistPublisher = entityManager.find(Publisher.class, publisher.getId());
         assertThat(persistPublisher).isNotNull();