|Japanese name:||人吉 善吉|
|Nickname:||Zen-chan, Medaka's Guard Dog, Club Typhoon, Heat|
Zenkichi Hitoyoshi is the male protagonist, childhood friend of Medaka, and the Student Council General Affairs Manager. He reluctantly joined for the sake of protecting Medaka. In the pilot chapter, Medaka assigns him to become the Vice President. Zenkichi always shows enthusiasm toward Medaka's cause for helping others, and he will punish anyone who opposes that cause. It is later revealed that he is the one who reformed Medaka into her current personality.
Voiced by: Yūki Ono