The story centers on Kazuna, an â€śaverage high school studentâ€ť who starts to lose control at the sight of blood, or even just a blood red colour (as seen in volume one when Yaegashi shows him a bottle of red paint). This problem is traced down to him being a vampire, like his lost sister, Chizuna, who he now turns to for help. Kazuna lives with his â€śauntâ€ť and â€śuncleâ€ť (both of whom are actually old friends of his father), after his mother died, and his father took Chizuna and left. Kazuna is friends with an aspiring artist named Yaegashi, who later learns about his condition. They both have feelings for each other at the beginning of the manga.