What's the work?
Yu-Gi-Oh is a anime/manga series created by Kazuki Takahashi in 1996 that spawned several other shows, it follows the story of Yugi Muto, a young boy with a talent for Duel Monsters who rises all the way to the top.
Who's the character?
Seto Kaiba is a major character in Yu-Gi-Oh, serving as Yugi's main rival as well as the show's deuteragonist (alongside Yami Yugi), and also the de-facto protagonist of the Dark Side of Dimensions movie.
What makes him a Shonen Rival?
Anti-Heroic/Anti-Villainous: Has saved his brother multiple times, as well as Yugi and his friends. He also teamed up with Yugi to defeat two Rare Hunters and has a soft spot for children.
Honorable: Despite being a massive jerk most of the time, Kaiba has lines he wouldn't dare to cross, with bullying and mistreatment of children being two things that pisses him off. He also develops a genuine respect for Yugi, considering him the only person on his league.
Tragic: Seto's parents died in an accident when he was just 3, as a result he and his younger brother Mokuba both spent a good portion in an orphanage, and even when he was adopted by Gozaburo Kaiba he was often abused by him, which led to him becoming the cold, arrogant and victory-obsessed man he is now.
Intelligent: Defeated his adoptive father in a game of chess after studying his playstyle so Mokuba could get adopted as well, he also planned a ploy to take over Gozaburo's company after he was gifted 10% of its share. As the CEO of Kaiba Corp he's often regarded as a genius in-universe due to his company's inventions.
Arrogant/Jerskish: And how, one of Kaiba's defining traits is how arrogant he is, his dismissive treatment towards Joey's skill as a duelist in especific is one of his most notable interactions outside of Yugi.
Pursues a Big-End Goal: Defeat Yugi so he can finally be the best in the world.
Cynical: Very distrustful and jaded of people's intentions due to his past.
Believes in the Power of Individual Strength: Thinks Yugi's talk about believing in the heart of the cards is bullshit, instead believing that the strength is in the individual.
Redemption Arc: Slowly softens to Yugi and begins treating him with more respect, and as more focus is put on his character he begins to move away from villany, instead becoming more of an anti-hero.
Is A Serious Threat/Villain: Pretty much the show's very first villain, being introduced stealing Solomon's Blue-Eyes White Dragon card and kidnapping him so he can defeat Yugi in a duel.
Veredict?
Very easy yes for Kaiba, in fact, I'm surprised he isn't in this wiki yet considering he's typically regarded as the other codifier of the Shonen Rival trope alongside Vegeta.
