Allen Rodol enters a tournament. He fights against an opponent who can seal their foe in a time-extended world. It only lasts one hundred years so it doesn't affect Allen. Next, Allen fights a true prodigy. Allen almost dies, but at the last second, he brings out his inner hollow or some sealed demon. I'm not sure, but it may be a demon king. Due to that, Allen is disqualified and suspended from school for a month.
The story is pretty good. There are a lot of tropes, and I believe the author borrowed from several other intellectual properties, but it all works out.
I enjoyed the book. Thanks for reading my review, and see you next time.