A 32-year-old male and the eldest son of the Akai family. He is an FBI agent and a master sniper. He wears a black beanie almost every single day; it is said to be rare to see him without it. He is usually blunt and quiet. Despite his stoic nature, he takes surprisingly good care of his younger siblings. He frequently drinks canned coffee.

A 28-year-old male and the second son of the Akai family. He is an exceptional Shogi player with an incredible memory. His memory is almost at the level of long-term photographic recall. His specialty is Shogi. He is usually kind and friendly, but he can be very serious when the situation calls for it. He has a bit of a gentle, soft-hearted vibe.

An 18-year-old female and the third child of the Akai family. Her specialty is Jeet Kune Do, and she is a high school detective. As a detective, she is very intelligent. She has a bright personality and isn't the type to go looking for trouble.

A 53-year-old female and the mother of the Akai family. It is said that she rarely shows a smiling face to her children. She is an SIS agent.