I think he is the ex from college. The one who nearly bedded Ikuro.
It’s all abt a young master who yearned for love since he experienced a fucked up childhood life where his farther got obsessed and sexually abused his old child (mc’s older brother) while his mother went mad and blamed it all on her pitiful mental-illed son and put hard pressure on the other one. And there comes a crazy mind and sadistic butler who enjoy seeing the person he takes a liking to suffer and torned apart ( I don’t want to use the word “love” since it’s fucking far from love by all means), so he decided to use all he gets to isolate the boy, by deepening the hatred between the 2 brothers, by pressuring the boy to get an heir knowing he can’t, by giving him to the old men to be broken, by pocking a hole on the keep-getting-better relasionship between ghe boy and his wife... and makes him feel like the butler himself is the only one who he can depends on.
And btw, the college friend who showed up at the end is not a cop, he is more like a reporter I think? And hope he comes soon to rescue the poor boyT.T
im sorry but i've forgotten who the cop? guy was at the end can someone please remind me (￣∇￣") and maybe of the whole plot in general lol