Oh boy, this manga is so interesting. Too bad it's not complete one and still updating, so...

I tought of Nights.... a little bit mabey....

And if its not yaoi but dark ambience, mysteries and detective.....Jiraishin
Its excelent. But not a trace of BL

I meant BL, but I like mysteries, so I'll check out both. ^^ Thanks.~

...for yaoi only some similarities also here
prison
http://www.mangago.zone/read-manga/under_grand_hotel/
http://www.mangago.zone/read-manga/aiso_tsukashi/
undercover
http://www.mangago.zone/read-manga/buddy_system/


But i wish there were more... I especialy like the undercover and mystery motive a lot

I already did read Under Grand hotel, that was aswell a good one. Thanks for the other tips though!