This Reboot Story

I usually don't pay attention to the story, but lately, I've been watching it seriously because Yanggung-i is cute. But it's so absurd that I can't even get angry. If you just listen to what the characters say, they sound more like a bunch of delinquents or villains than heroes. Yanggung-i pulled Yong-gyu out of the water, and then saved San-ha and Ye-seul by shooting zombies behind them with a bow. But Ye-seul doesn't even remember Yanggung-i, and Yong-gyu says he doesn't need to remember someone who's not good at anything. I don't understand why he'd say that. Yanggung-i was the ace until their first year and only became second because San-ha was better. So, is the line 'not good at anything' really accurate? I also don't get what this story is trying to show. Is it trying to depict the dangers of school violence?