
I think a lot of people are misunderstanding something; the ML is not in love with the mc yet.
The reason he is doing this experiment is out of sheer curiosity. He might have fun teasing the MC or hang out with him, but thats not love.
The MC on the other hand is crushing on the ML but conflicted on their relationship and how to feel. ML is purposely being a dick and trying to make cracks in their relationship to test this 'name bond' that people talk about. Yes this might bite him in the ass later but atm that's not a big deal for him

MPREG POSSIBLE IN THE DEMON WORLD??

Here's the official site for the 2nd novel. Dunno if there's any free raw somewhere.
https://page.kakao.com/content/65962588?tab_type=product
Ignoring the age gap, i would like another story where mc wants to die, and ml/fl who promises to grant them death instead falls in love with them. Its also interesting how mc realizes that ml might fall for him and in turn not be able to kill him, and instead of blushing and stuttering, he is.... dissapointed.
Have you tried the story Pieta?
It's a killer x immortal that wants to die
https://www.mangago.zone/read-manga/pieta_daong/
Pieta is much more kink oriented than story tbh, but it's a good read if you're there for the smut
Well don't mind if I doヾ(❀╹◡╹)ノ~
it's good in the "oh that's so... hot, actually.." way