Jahyeon Jo (조 자현, Jo Ja-hyeon) is a member of the Humming Bird Crew and a junior at Sunny High School.

Jay is a young man with short, straight black hair cut into a mullet. He usually assumes a serious and emotionless expression. He appears cold hearted, but very much so cares about the friends he has and his little brother. His minimal expression of emotion doesn't allow him to articulate his feelings very well, but sometimes his few words mean a lot. His typical school uniform consists of dark trousers, a white shirt, and a red blazer. His casual clothes is composed of a variety of T-shirts, hoodies, and sportswear. Since he is farsighted, he wears black-rimmed glasses.

One morning at school, Jahyeon is approached by Minu Yun who invites him to join his biking crew, he declines and Minu takes his leave.^[1] Jahyeon returns to studying but the invitation makes him recall memories of his uncle. At the end of the day, Minu returns and informs Jahyeon of one of his crew members who had been trash talking his bike and that he had been challenged to a race. Minu leaves, telling him where the race would take place should he change his mind. Jahyeon arrives at the park and completely ignores his opponent. He is introduced to Junsu Lee who explains the mechanics and the route of the race, then the two take their place at the starting line.

         Jahyeon drifting.

When the cog hits the ground, the two are off and the race begins. Taejin Kim intentionally bumps a traffic cone in his direction, but he quickly maneuvers his bike to evade, bouncing atop an oncoming car - a move that leaves both Junsu and Taejin in disbelief. Approaching a sharp turn, Jahyeon skillfully drifts along the turn, securing his lead in the race.

A downhill is approaching, and they ignore Junsu's shouts for them to slow down. Jahyeon speeds downhill and shifts his bike to skid at the bottom, he kicks off to propel himself forward. Taejin follows suit but he is unable to control his speed or his bike and crashes against the gate. With his opponent unable to finish the race, Jahyeon slows down and leisurely makes his way to the finish line. When he arrives first, he is quick to leave, but not before reminding Minu not to bother him with any more crew business at school.^[

Jahyeon beaten up by Taejin and his gang.

The next day, he crosses paths with Minu in the school hallway, who quickly congratulates him on his win, having seen the footage from the race. On his way home, he is forced to make a quick stop when he gets a flat tire and is suddenly ambushed by Taejin and his friends. He has forgotten who the three are. Pissed off, Taejin kicks his bike and Jahyeon retaliates with a punch to the face. They start a fight, but he loses, and they beat him up. Taejin tries to intimidate him, but Jahyeon talks back, the former is about to beat him up again when a student from hisclass, Hannam Kang, intervenes and the three leave.

Hannam knocks Jahyeon out.

The two are soon approached by Minu and Hannam explains what had happened. Minu sincerely apologizes for getting him involved in his crew's business, but he brushes him off. Minu tries to get him to seek medical attention, but he continues to refuse. Fed up with the back and forth, he is knocked out by Hannam and carried to the pharmacy.^[4] He wakes up to the of them snooping through his room, he demands they leave and they do, but not before corrupting his                                              computer.

Junsu speaks with him the following day, explaining what had happened within the crew and asks for his help with their upcoming race. Jahyeon refuses and Junsu leaves, telling him where the race would take place if he cared to show up.

Source : https://windbreaker.fandom.com/wiki/Jahyeon_Jo