This hero is a fake. Agetha is sealed within the sword that the fake hero is using. One of the hero's party is the key to releasing Agetha. Also, two of the hero's party are traitors and are the source of a number of bad endings. They will kill the fake hero and it will take awhile for MC to find a solution to them through multiple resets. After that, there's a bunch of resets involving the two Agethas forcing resets by killing the MC. Eventually, Agetha agrees to be sealed again for 100 years to avoid the world ending and MC returns to the present.