Who are they?

Who do you mean?

I don't recognise the characters in the latest chapter, are they new to the story ?

Not really you should have already encountered them if you've read the whole story. The big buff man is Sen he had a not so nice relationship (also sexual) with Manji and was also in the firebrigade. And the other one is the brother of the former tattoo artist from Sen. Sen loved him, I think. It does look more like Lust then love for me but I think there was something there if he kept one of his bones.

Thanks I remember them a bit now, I think I'll need to reread this (๑•ㅂ•)و✧