the tattoo in earlier chapter and this chapter is depicted on different hands (first left, then right), only difference is in that curve pointing toward elbow or the fingers.
@randk2k1
the creator is Korean, so I'm assuming the characters and setting are Korean as well.
It's just that the characters were given japanese names for the translation.
The trope of unmonitored bullying/fighting going on in schools is big in a TON of webtoons/manhwas, the reason being that bullying is a real issue in Korea.
Dont remember the chapter but the school nurse stated at one point that the teachers know about the shit going on. But could not do anything about because of the principle of the school or something.
So it seems to boil down to the eastern culture of cant say anything back to the once's above me even if a few kids might die. (and seeing that in irl this kind of culture caused a plane crash im not surprised if this happens irl aswel.)