I remember the manga has the tag yaoi, romane (?) and slice of life. I also recall the plot being: a yakuza falling in love after receiving help from a laundry worker (the yakuza lost a fight and his wounds were taken care of at the worker's home). Fluff and flirt ensue until one day the worker has to attend a marriage interview. The yakuza becomes devastated, and when trying to find the worker, in the rain, he sees the lady in the interview next to the worker. The yakuza runs away and gets a cold after. The worker, wanting to clear up misunderstandings, goes to the yakuza's place. Once everything is clarified, they become lovers.
TL;DR: yakuza likes a laundry worker for his kindness, slice of life, yakuza has black hair and the worker has orange hair. Also, the yakuza has a dragon tattoo on his back.
I'm back! I think I found it. It's also one of my favs: https://www.mangago.zone/read-manga/midnight_rain_ctk/
if it's not it, tell me and I'll go back to check the rest of my list!
i love how the seme came first, it's refreshing to see the uncool side of the semes in yaoi ^-^, gives you off the feeling that there's no "girl" in the relationship.