Former high school classmates, now adults, hold jealous thoughts, hidden intentions and lust for revenge. Graduates from a high school have held reunions since they graduated 10 years ago. The high school itself is located 2 hours from Tokyo by train and past reunions were held by different teams for different areas. An upcoming reunion is the first time where everyone will gather again.

Little Trip: Chairperson Ayako and Yuki, who sometimes skips school, become close. They run away. Rakugaki Uwagaki: Satomi used to be a member of art club, but she stopped drawing. Due to a cultural festival, she decides to draw again. Baion: Kuroi likes recording the sounds of daily life. One day, she meets Rika. Rika begins to enjoy recording the sounds of daily life with Kuroi.

Hajime finds it difficult to graduate to the next grade at school. His friend Miyuki tells Hajime to study at a private school which is famous for its strictness. At that school, Hajime uncovers a death caused by non-natural reasons. He's challenged by a genius crime producer. ~~ Based on the manga series "Kindaichi Shonen no Jikenbo Gokumon Juku Satsujin Jiken" by Seimaru Amagi and Fumiya Sato.