Realizing this is one of my favorite novel settings http://gravitytales.com/the-beginning-after-the-end/ he's not really learning anything at the school though.
http://www.novelupdates.com/series/heaven-awakening-path/ MC goes to school but never attending a class and almost drop out. Its funny when th MC come to Final Exam and destroy the tower. this WN similiarty with mahouka