Shikabane-gatana

A middle schooler named Tsuranuki Tsutsuki faces a daily routine that includes school, chores, and battling zombies in a Tokyo overrun by the undead. When his sister is taken by them, he takes up a gun to rescue her. He meets a high school girl who wields the Corpse Blade, a weapon that grants her control over powerful abilities. Together, they fight through hordes of zombies in hopes of reclaiming a normal life. The story follows their journey as they battle for survival and Tsutsuki's chance to save his sister.