Has it been THAT long

Yo, me too, I have a faint memory about the story. I'll share with you, maybe that can help (ofc, only if you're not planning to read it all again).

The black haired guy asks the mc to date him or be his muse (more specifically, his hands, the black haired guy loves mc's hands), and the mc accepts bcs he's broke. Later on, the mc gets wary about the black haired guy bcs he's constantly changing and taking a lot of pills, so he gets involved in this whole thing and discovers that the black haired dude has multiple personalities. They then try to figure out everything and that's just about what I remember ( ´◡‿ゝ◡`).