Mihai Mihaeroff (ミハイ・ミハエロフ, Mihai Mihaerofu?), the "Weepy Old Killer", is a retired assassin and is considerably older than the rest of the cast. Despite this, he retains a muscular build in addition to scruffy facial hair. Due to his years as an assassin, he remains calm under pressure. Mihai has a long-standing friendship with Kiri, the owner of a local restaurant and former prostitute. Ten years prior to the start of Dogs, he was a hired assassin for a gang boss and became mentor to the boss' son, Ian. During this time, Mihai was romantically involved with the prostitute Milena, but the relationship ended when Ian grew into his teens and murdered her. In the Dogs chapter Weepy Old Killer, Mihai confronts Ian and, after failing to protect him during an assassination attempt, admits he was afraid of losing Ian.
Of the four protagonists, Mihai is the most level-headed, experienced, and least anti-heroic of the group. Despite his old age and being human, Mihai has skills that equate or even exceed most of the entire cast, including the other four. Even as a skilled assassin, Mihai has a terrible sense of direction and has a constant run of bad luck. He and Badou share a close bond along with Kiri and Mimi, and also shares concern for Heine and Naoto. So far, his link to the underground is not as deep as the others, but Richter Berthein seems to know a great deal about the assassin. He is voiced by Akio Ōtsuka on the drama CD and in the anime adaption.