Kiba o Muku Ookami (S01E23)

After defeating Arundo Akamatsu, Kenshin returns to the Kamiya Dojo and sees Hajime Saito. Hajime had introduced himself to Kaoru and Yahiko as Goro Fujita, the police officer, and they had invited him into the Dojo without any suspicion. Hajime criticizes Kenshin and the others for their naivety. Over the past ten years that Kenshin had washed his hands of manslaying, Hajime had honed his killing intent and skills as a hitman, and now Hajime's ferocity was aimed at them. (Crunchyroll)