The MC is the hero who saved the world from the hundred years war that was raging on between humankind and monsters pretty much alone. On top of that he is labled as a saint/saviour because he is the one who again single handedly keeps saving the empire by doing reclamation work, save them from food shortages, and rebuilding the destroyed villages/towns.

Eventually the MC wants a cushy life and joins the royal mages but because of how popular he is they get jealous and starts hating on him. So they decide to frame him for poisoning the duke (the emperors brother) and thus have him executed. But they don't really have any evidence of him actually doing the deed outside of the fact he lacks an alibi and was holding some strange seed when they caught him (presumedly it was what the poison was made of) but they didn't have any real conclusive evidence outside of just saying the MC did it!

But it somehow works anyway, especially since the MC is happy to get kicked out of there, but they can't execute him because of his previous deeds so he only get's most of his stuff confiscated, fired from the royal mages and exiled from the empire.

This part just made me go huh? Like the MC is not like some MC hiding his powers or brings some unknown benefit to people that makes them think he's useless when he's not. But they just up and banish the single most powerful person in the world who was seemingly 100% loyal to the empire, though mostly seemingly because of his beta nature, and brought a bunch of benefits to the empire as a whole. Later on this of course back fires on the empire with starvation and whatnot but in this case I can't stress enough how everyone already knew that the reason ppl didn't go hungry was because of the MC....

The empire or well mainly the royal mages of course later on takes on the villain position.