S1·E10 It's Called Amnesia

Ota has a strange dream where he kills his team mates who have all become criminals. He wakes up to find himself in Shinshi's house where Hiromi, Asuma, Shinshi, and Shige are dead from gun wounds, and Ota is holding a gun in his hand. He runs screaming from the house, but he soon can't remember who he is. Did he kill all those people? He looks in his wallet and because he has Shinshi's wallet, he believes he's Shinshi. Meanwhile the SV2 search for Ota. Goto believes he has amnesia. They must find him before he hurts someone else or himself.