Kinjiro

Araki did not draw a finalized character sketch for Kinjiro, but he describes him as being slightly overweight.↗

Kinjiro is a boy who likes mushrooms and knows an abnormal amount about them. Despite his overweight build and strange obsessions, Kinjiro is surprisingly popular with girls. Since his father is an incredibly successful genius chef of a 3-star restaurant, Kinjiro has an inferiority complex toward him, resulting in a twisted and distorted father-son relationship.↗

As a villain, Kinjiro's motivation comes from a basic desire. He wants to make a beautiful, wealthy young lady who frequents his father's restaurant his girlfriend. To achieve this, he is highly manipulative and scheming, willing to use dangerous, mind-altering fungi to trap her or slip them into her food to force her into a relationship with him. Araki notes that as his schemes escalate, Kinjiro becomes a "really dangerous guy."↗↗

Abnormal Mushroom Expertise

Kinjiro knows absolutely everything about the mushrooms that grow in his region. While technically an amateur, his knowledge borders on the abnormal. He knows which mushrooms are delicious or disgusting, which ones are lethal, and most importantly, which ones possess hallucinogenic properties, erase memories, or alter human senses. He weaponizes this knowledge, using the natural mycelium network to set traps or slipping undiscovered, sense-altering mushrooms into his targets' food.↗↗

Hallucination Inducement

While brainstorming how Kinjiro would work in a JoJo's Bizarre Adventure -esque setting, Araki suggested Kinjiro might awaken a supernatural ability that allows him to induce hallucinations through the leftover mushroom sauce on a customer's plate.↗↗

Araki created Kinjiro while explaining how to make a villain even when there is no existing protagonist, theme, story, or world. While thinking of what kind of villain to create, Araki noticed a book about mushrooms on the bookshelf in his workspace and began with the simple idea of a boy who likes mushrooms. He says that if he had noticed a book about dinosaurs instead, the character might have become a boy who liked dinosaurs.↗

Araki chose to include the kanji 菌, meaning "fungus" or "germ", in Kinjiro's name because he felt that a manga character with such an unusual character in his name would catch the reader's interest.↗