He is a judge and a childhood friend of Muhyo's. He is a pervert who enjoys trying to guess girls' cup sizes (his first appearance was him squeezing Nana's breasts). Yoichi appears to have a crush on Nana, which is unfortunate, since she considers him a creep. However, underneath this exterior resides his experience and wisdom that rival Muhyo's. Yoichi had offered to be Muhyo's partner, but Muhyo had already chosen Roji instead. He's an expert at every type of Magical Law except for Execution.

(Description taken from Wikipedia)