Seraph of the End, Vol. 3 by Takaya Kagami

[Viz] In a post-apocalyptic world of vampires vs. humans, Yuichiro brings vengeance upon his vampire overlords! After trumpets of the apocalypse proclaim the fall of humanity, vampires arise from the shadows to rule the earth. Yuichiro wants just one thing—to get revenge by killing each and every vampire. Yuichiro survives the trial to acquire Cursed Gear—demon-possessed weaponry that is humanity’s only hope for combating the vampire scourge. But times are dangerous, and instead of getting to celebrate his newfound power, Yuichiro and his friends are given their first mission: head to Shinjuku and investigate vampire activity. Unbeknownst to Yuichiro, Mika, his best friend and now a vampire, is headed for the same place.