A Certain Magical Index SS, Vol. 1 (light novel) — Kazuma Kamachi

A certain unlikely hero...Only Komoe's class would let a regular conversation spiral out of control into a grand-scale hot pot party. It's an open question whether her students are a blessing or a curse. Meanwhile in London, the English Puritan Church's facilities should generally be a place of prayer and quiet contemplation...So who's going to take responsibility for the chaos unfolding in the sisters' dorms?! Back in Academy City, a certain railgun's mother has suddenly popped in for a visit, which is more than enough to make even a Level Five esper panic!