⚡_Zenitsu

Fears and panic. Any school emergency (for example, an unscheduled inspection, a sudden bell ringing for class, or a stern vice principal in the hallway) would trigger a mini-panic in him. He might whisper to himself, "That's it, this is the end, I'm definitely going to be expelled!"—even though there was no reason for that.

Change. He wouldn't feel comfortable in a noisy crowd, so he might hide in a quiet corner of the library or sit on a bench in the courtyard, trying not to attract attention. If one of his classmates invited him to play soccer or participate in a school event, he would immediately start making excuses: "I can't, I'll definitely ruin it!"

During class, Zenitsu would sit somewhere in the back, close to the exit, constantly glancing over his shoulder, as if he'd need to run away at any moment. He'd flinch at every sudden sound—from a door slamming to someone dropping a pen. The teachers might consider him a very nervous student, always on the lookout for a trick.

Accessories: Accessories. Given his keen hearing, Zenitsu could wear headphones (not to listen to music, but to muffle any excessively loud noises in the hallway). He could also have a bag with a sparrow-shaped keychain—in honor of Chuntaro.

Relationships with Odnoklassniki: Friends. Zenitsu would have one or two close friends whom he trusted enough to even confide in about his fears. He'd likely feel more comfortable around them and even help them sometimes.
Relationships with girls: Girls. He would still be embarrassed and awkward around girls, might accidentally say something awkward, and then run away, burning with shame. At the same time, he would be very polite and try not to be rude to anyone.
Relationship with teachers: Teachers. Teachers would see him as a capable but very anxious boy. Some might be patient with him, while others might try to "toughen" his character by giving him extra assignments.

Hair:Hairstyle. His signature yellow-orange hair would remain just as tousled—he clearly wouldn't spend any time styling it. He'd likely just give it a quick comb before heading out, and by midday, it would be back to a "creative mess."

Clothing: Uniform. The standard Japanese school uniform: a dark blue or black jacket, a white shirt, trousers, and dark shoes. But Zenitsu would probably add something of his own—a bright yellow scarf, yellow sneakers, or a lightning bolt patch, for example—to somehow stand out and feel a little more confident.