The Asterisk War: The Academy City on the Water, Vol. 2 manga (The Asterisk War Manga, 2)

Having begun attending Seidoukan Academyone of the six magical schools in the city known as the AsteriskAyato Amagiri begins the task hes truly there to accomplish: investigating the disappearance of his elder sister! Hes given a powerful weapon that she once wielded, and it seems like hes on the right track. But when he and Julis are attacked in broad daylight by mysterious forces, its clear his search isnt going to be as easy as hed hoped...