Sure, this chad is Kang Han Soo. The premise of the story is that people are sent to worlds to save them as a "test" of sorts. While these worlds are real to some extent, they also can be repeated/reset if someone fails their test and needs to start over. Kang Han Soo had to start over (lol). He spent the first run training for years with his "comrades" but got pissed with their annoying anime/manga/webtoon isekai tropes (Violent Tsunderes, Brutal training for the newly isekai'd, etc). So he killed them all before beating the final boss. He got an F in friendship so he had to keep doing this test multiple times to get a passing grade. (One of those times included a buddy to get isekai'd with, but that innocent glasses kid ended up only thinking with his lower half or.......with nothing). After multiple retries we see him get the score, and he's......not sent back.

Got put into a "holding area" for all the hero children. He did not play nice with those hero children during that event.

He was finally sent home but got killed by a grudge-holding figure from a past iteration of the world he was thrown into. Making him get isekai'd again

The black box/glitch power he has is the only thing keeping him from getting torn up by the rules set by the administrators, and part of the story is figuring out what its purpose was. The first hero of that world supposedly created that power, which is why MC has been uncovering that guy's past a little bit

I'm missing some if someone wants to take over be my guest lol

basically they are training hero's in copy worlds when the og hero was gigachad mccreative mode

Spoiler: He will find something shocking in next 2 chapters and change his direction again.

Mc is having an existential epiphany.
He's thinking about the limits of his skills given by the system.

The mc found a machine that let's him go home, and he's been looking for ways to go home