Seraph of the End, Vol. 2 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. Now that Yuichiro has earned his place in the Japanese Imperial Demon Army, he prepares to undergo a fiendish test to acquire the most powerful and deadly of humanity’s weapons against vampires—Black Demon Series Cursed Gear. Meanwhile, the vampire nobility welcome a new member—Mika, the best friend Yuichiro thinks died in their escape but who has his own bitter story of survival.