Jouji is the shortest of the five; due to his frail constitution, he is rather weak and gaunt. No matter what he wears, Joe is always seen wearing a hood over his head that casts his eyes and most of his features in heavy shadow. The hood itself is revealed to be completely detached from any clothing, thus enabling Joe to wear it with anything — even in the pool. During his imprisonment, he wears the standard male prison uniform of white striped overalls paired with his signature hood. When Gakuto triple switches with Joe and Chiyo, it is Jo who impersonates Gakuto by wrapping bandages around his forehead and wearing glasses. After release from prison, Jouji goes back to wearing the standard male uniform.

Joe is the sullen oddball of the five boys, who struggles to fit in outside his group of friends (and sometimes within). He suffers from a bloody cough due to severe stomatitis, though the disease is neither chronic nor physically debilitating to him. However, his canker sores do affect his speech, with bloody coughs often punctuating his sentences and interrupting his speech. Despite being the quietest, Joe is actually one of the more lecherous of the five, reflected in the crass way he speaks and makes jokes.

Joe also has a love and appreciation for ants to add to his quirks, going so far as to name the ones he keeps in his ant farm and being able to tell them apart — though they all look alike. Towards his friends, Joe is shown to be accepting and supportive.