
Oh come on, if you were all summoned to another world and forced to do shit against your will, you'd all be like like the mc. You'd all want to quickly defeat the demon king as fast as possible so that you can go back to your comfortable modern life, no matter how shitty it is. Most fantasy worlds are set in the medieval times, so just think about it; no wifi and internet, no modern toilets, shitty wooden beds, stinky people, stinky towns and diseases everywhere.
It'd be even worse for the hero since they have to travel to these stinky places and sleep on the roads, all the while constantly fighting monsters. You'd never get another peaceful wink of sleep again.
Also, in most hero adventures all your comrades are annoying as fuck. Girls trying to constantly get your dick and nag you as well as try to injure you for no discernible reason. And if your lucky enough to get a guy companion, they either act like an omniphobiac coward or a muscle head who only knows how to talk with their fucking fists.
If your a girl hero, you'd have to deal with handsome guys trying to make you theirs, love triangles, love squares, love whatever fucking shape, and other jealous girls who'll try to ruin your life because you made eye contact with their crush.
If you're a "reject" hero, you have to deal with being ostracized by society and the same shitty comrades like the normal hero except they now have sad backstories. Boohoo cry me a river, there are people out there suffering worse than you.
Do you really think you'd all act like a goody two shoes or an edgelord who wants revenge? No, you'd all act realistically. And while some of the mc's actions are a bit exaggerated, his actions are completely rational since not only does he have to repeat another ten years of being a "hero", he has to deal with his shitty comrades again.

Yea that was always my thought in these stories. Kidnapped me and now you want to force me to defeat the demon king? How about no? I'm not about to put my life on the line for my kidnappers. I'd sooner try to take over or destroy the kingdom that did this to me. Screw your criminal selfish country. I'll make my own, with blackjack. And hookers. :P

I think that the teacher started killing little kitties at first then killed a person, then started killing cats again as to not arouse any suspicion.
The reason that spirits follow around certain people around all the time might be because they have a connection to that person. For example, the spirit that said "You lose" after mc wanted to start a race died and they might've been really competitive. Or the spirit of the mc's dad, he was there because of his family.
So let's get back to the teacher here, the cats don't really do anything but follow him around while the giant spirit is the human he killed. The giant spirit, I think, put it's hand or whatever inside him cuz it wants to kill him.
Elf princess (little sister of main girl) is a T H O T