Ririko Seko (Kuroki Haru),who works in the accounting department of a major publishing company, Kusunoki Publishing, is not very good at understanding other people's feelings or reading the atmosphere, but she has a strong desire to learn about the world and other people. In the accounting department, she is also known as Cerberus, the watchdog of hell, because of her strict checking skills.

• Haru Kuroki
• Anna Ishii
• Junpei Mizobata
• Toru Nomaguchi
• Shuhei Nomura
• Hayate Ichinose
• Kanichiro
• Masanobu Ando