I Kept Pressing the 100-Million-Year Button and Came Out on Top, Vol. 3 (manga)

Days after the turmoil at the Elite Five Holy Festival, Allen, Lia, and Rose have been suspended from school and are busying themselves with witchblade activities. As part of their training, the three students must complete a series of monster extermination quests. Much to their surprise, however, at one of the towns they''re summoned to, they run into a very familiar prodigy-