Blackguard 2

What does it mean to be alive? Minami—a young Guard who's rumored to be invincible—thinks about dying every day. In a world overrun by ape-like creatures called shojo, he has battled alone and thrown himself into all kinds of danger. And no matter what horror he's faced, he has betrayed no hints of fear, resentment, or despair. But when his newly assigned partner Miyaji gets bitten, Minami panics. He swings the Black Sword and severs Miyaji's leg to stop the infection from spreading and turning his partner into a shojo. But now, left with a grave injury, Miyaji is on the verge of dying—and Minami, perhaps for the first time ever, is paralyzed by the thought of death.

Volume 2 of the Blackguard manga series by Ryo Hanada.