Yozakura Quartet Vol. 15 (Kodansha, 2017)

Knowledge begets evolution! The kotodama user origin arc commences! By gaining new knowledge, so, too, does a kotodama user gain strength. Bibliophile, Kotoha, takes a trip to the senate's library, where she meets an elderly librarian who also happens to know the truth about kotodama users. But just as Kotoha is about to pick her brain, a girl wielding weaponized sound invades the senate, leaving her no choice but to intercept. And so, the sanctuary of peace and quiet becomes a battlefield of sound and voice.