Jirō Saemonsaburō (佐衛門三郎 二朗) is a blacksuit part of the group Tonegawa manages in the spin-off series Chuukan Kanriroku Tonegawa.

He is known for being one of the youngest in the group and for his knowledge in handling modern technology such as creating Powerpoint presentations.

He is credited for inventing Restricted Rock, Paper, Scissors.