So after reading to ch27 I went looking for spoilers, found the whole novel (a pdf in Spanish, it was a pain trying to get the whole file converted so I could Google translate it).
The Prince is basically the final boss. I was honestly shocked at how easily everything else was solved tbh. And vol 8 of the novel (final volume) made me dislike the ML a little bit.
I don't know why people keep talking about Ijin resting, he's literally a top dog ex mercenary, of course he's going to get into a lot of messes. He probably does rest a lot in between plots, but the author only lets us see the action (most of the time, with some normal high school time sprinkled in.). Like, I don't think he's literally jumping from one baddie to the other the next day. There's probably days or even weeks in between, but this is an action manhwa, not slice of life.
ik if they see ijin resting when the title is mercenary then they would nagged abt how boring it was