Ken Oyanagi

Ken Oyanagi is a minor antagonist appearing in Part IV: Diamond is Unbreakable.

Personality
Ken's wish is to become an adult who is respected just as much as Rohan. He has no real knowledge of stands in the start but he quickly learns more as the match progresses. He is decisive in his actions, willing to sacrifice himself after being defeated and taking a baby hostage to get another match against Rohan. He heavily believed that luck was on his side.

Diamond is Unbreakable
Ken fell off a telephone pole resulting in a hole in his left cheek. This hole was likely caused by the stand-creating Arrow that Yoshihiro Kira used to create new stand users in Morioh. Being a huge janken (Rock Paper Scissors) fan, he challenges famous mangaka Rohan Kishibe after running into him. Rohan, very annoyed by his presence, uses Heaven's Door to cheat and chase him away, but Ken appears again, and Rohan plays a game in the hopes that if Ken wins, he will leave him alone.

However, Ken's main intention was to win over Rohan's "mind power" by defeating him in janken, as he believes it would mean he would surpass him as a person as well. When he finally wins after several defeats, his stand absorbs a little of Rohan's stand power and starts to learn about stands. He is tricked by Rohan in their last match, who teaches him how to surpass himself and turn luck to his side instead of just relying on it. Thinking it was unfair, he takes Shizuka hostage and Rohan agrees to battle him again, but this time Ken is defeated fair and square.

Not accepting his defeat, he throws himself in front of a truck, but Rohan jumps with him and both are almost ran over. The truck driver misses then after accidentally having his vision blocked by Yoshihiro Kira. Seeing that luck is really on Rohan's side, Ken admits defeat. Rohan then says he likes Ken, liking characters who takes decisive actions.

Trivia

 * According to Heaven's Door, Ken reads Shounen Jump every week and is in 6th grade in his school.
 * Ken appears on the cover of volume 40.
 * During the climax of his fight with Rohan Kishibe, Ken said "Good!", a clear reference to Daniel J. D'Arby.
 * He and Mirashon's stand are the only characters so far to make a reference to a past minor-antagonist, Daniel J. D'Arby (using his catch phrase "Good!").
 * This is evident as His, Mirashon & the D'Arby's stands revolve around gambling (Marilyn Manson, Osiris, Atum).