Responses
Could be this one? http://www.mangago.zone/read-manga/killer_the_housemate/
I haven't read it, tho the plot seems to match
Yes thank you
The seme is a psycho n he murders people ( for others ) . Then one day his next target was a guy who looks similar to the uke ( the uke looks like so many people , as in the uke has a common face in the manhwa). So he mistakenly attacks him but later realise that he got the wrong guy. But now he can't let the uke escape. So they started living together ( next door ). The seme is a little dumb though a psycho which makes the story funny.