Vampxia

All college student Sena Minazuki wants is a modest, ordinary life. But one night, he returns home to find that his once-doting older sister, Ran, has undergone a drastic change—and suddenly attacks him with deadly intent. Just as she’s about to overwhelm him, a mysterious armed organization storms in and opens fire on the rampaging Ran.

Sena soon learns that she was suffering from "Vampxia"—a government-classified disease that turns ordinary humans into bloodthirsty monsters with terrifying strength. Unfortunately, the truth arrives a little too late... because Sena has already begun to manifest symptoms himself!

(Source: Square Enix)