Yoichi is a former student in the M.L.S. He wears a red shirt (or sometimes white) with black pants. His hair colour is black, shoulder-length, and he wears a headband on top to move his hair back. He wears a black sweater and black pants with ear muffs instead of his headband during the Winter time. He has gray eyes and black pupils.
Yoichi is somewhat of a womanizer, and is popular with the female Magic Law students. He likes to grab girls' breasts (particularly Nana's) and is able to determine their bra sizes simply by grabbing their breasts.
Besides this, he can be extremely focused. Known for his skill, he is called the "Prince of Magic Law" by some. He can be annoying sometimes but he is also a smart judge, he plans his attacks in at least one second or two. In that time, he can set up a decent trap or plan but this is because when he noticed Muhyo's skill bloomed, he kicked into high gear.
Yoichi appears to have a crush on Nana. 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. It is also shown that Yoichi has become smarter and faster since Muhyo's talent bloomed.
Yoichi was originally a student in the M.L.S, with Enchu and Muhyo. His teachers were Rio Kurotori and Page Klaus, with whom he had loyalty to. He usually stayed in the M.L.S with the other students but he is mostly with Muhyo and Enchu. He liked to play games unlike Enchu, who always studied and did his homework. He wasn't a smart student in the MLS like Muhyo, they were both dumb, without Enchu, they wouldn't been getting their work done. Once when their teacher got angry at them, Yoichi couldn't solve the question, nor could Muhyo, but Enchu solved in a few minutes. He liked Enchu a lot that he was very sad to know Enchu went to Forbidden Magic Law, he saw Enchu go psycho and he couldn't stop him, and later he couldn't find Enchu, so he ran to Page Klaus for helping him find Enchu, Page Klaus accepted his offer and now Yoichi has never stopped working in the investigation for Enchu for 2 years, he has given up freedom and free time and comtributed a lot for the investigation. He found Muhyo and figured out that he was also wanting to free Enchu so he let Muhyo know about the conditions every time Muhyo asked for the information about their investigation for Enchu.When he was looking for the Writ of Passage from Isabi with Page, he lead the team when it came to taking down Buhpu and defeating his puppets, his partners were Judge Imai and Asisstant Judge Ginji. He made all the plans at the lat minute so that he can prove it to Enchu that he didn't have to be an Executor to save his mother, he could've done it as a Judge, so he made Kiriko summon Hellsquitos to spit out the truth about the Cortlaw family. Once they save Enchu, Yoichi was sad that Enchu has to live in the Arcanum and didn't want to say goodbye to him. He still tries his best so that one day Muhyo will accept him as a partner.