Koki Kariya (Berserk) is a Boss in The World Ends with You. He is fought during Week 3 of the Reaper's Game.
Strategy
The fight with Koki Kariya (Berserk) is considered one of the toughest fights in the game due to the fact that, as a properly "synced" duo, Kariya and Uzuki have their own light puck when both are in battle, and the two can also access a Fusion attack. Beat should use evasive action when Uzuki gets the puck and try and interrupt Kariya's attacks when he has the puck. If he isn't hit for a while, the light puck goes away, similarly to Neku's. Neku should use the same strategy as he would use for the non-berserked Kariya. Beat should defend whenever necessary and try to get as many Fusion Stars as possible. It should be noted that Koki and Uzuki use the same attacks as they did in the previous fight. Their most powerful attack the player will see during this battle is their fusion attack, which can do high HP damage, so heal quickly afterwords with a Cure Drink pin.