Capumon King! Showdown for the Top!!

Synopsis

When Honda is seemingly killed by one of Kaiba's death traps, an enraged Yugi battles Mokuba, Kaiba's younger brother, in a game of Capsule Monster Chess. This is the first time Jonouchi and Miho see his alter-ego. After Mokuba loses and faces a Penalty Game where his soul will be devoured, Yugi saves him, ultimately going to Death-T 5 to defeat Seto Kaiba in a game of Duel Monsters. (Source: Wikipedia)