From MangaHelpers:

Sadayuki is a high school student on his morning commute with his girlfriend Hibino and his childhood friend Akari, enjoying the good life that comes with being with the top beauty in school and very close childhood friends with the cutest. Although often envied because of his relationship with the girls, he is considered a good guy as he always helps those in need. An 'ally of justice' and self-proclaimed hero, Sadayuki is eager to give a helping hand in the name of justice.

Sadayuki finds things take a strange turn when Akari appears in front of him, covered in blood. Even stranger are the visions he starts seeing. As he is chased by a mad killer, the visions become more vivid and deadly.

The stage is set. The cast has been gathered. The story follows Sadayuki's struggle to survive and save his friends. [Kamas]