Kaiba Seto is one of the main characters of Yuugiou, and is the the eternal archrival of Yugi. He is cold and ruthless, but he had a tragic childhood, so maybe that explains why he doesn't trust people so easily. But there is good in him.
Seto lost both his parents early in his childhood, and was sent to the orphanage with his younger brother, Mokuba. He was exceptionally intelligent, and all the families wanted to adopt Seto, but he refused to separate from Mokuba.
Seto craves power and has the determination to make things happen.
When he learned of the existence of the 3 legendary god cards and got his hands on the Obelisk, he becomes obsessed with getting the other two and creates the Battle City Tournament in order to win them for himself.
Kaiba Corp specialized in dangerous military weaponry in the past, but Seto turned it around and focused on taking games to a whole new level. He created the famous duel disks and brought the card game alive with Kaiba Corp's hi-tech software. He also sponsors duel tournaments, and created a Duel Monsters-themed amusement park, and dreams of opening more around the world.
Underneath his icy cold personality, Seto does have a heart - which is evident in the way he looks after his younger brother. They grew up in tough times together, and only have each other to depend on in this world. Mokuba is the only person he can completely trust, and Seto has become more of a father figure to him.