Awaking to chaos and carnage while on a school trip, Yogiri Takatou discovers that everyone in his class has been transported to another world and has had powers bestowed upon them by a mysterious sage.

With the vast majority of Luu's powers restored and the UEG dead, Yogiri and Tomochika are on the verge of finally making it back home. However, in order to undo the damage wrought by the UEG's rampage, the Great Sage resets the entire world to the moment Yogiri's class was first summoned. While the people Yogiri killed remain dead, everyone else is brought back to life, including Sion, the Sage responsible for summoning his class in the first place. Having retained her memories of her previous encounter with Yogiri, she agrees to help him and Tomochika collect the Philosopher's Stones once again. While things seem poised to go more smoothly this time with her assistance, it doesn't take long for another Sage's carelessness to throw the entire world into a brand new kind of chaos.