Blue. The color made him angry. The blue of his eyes, the blue of his breath. Sanemi Shinazugawa hated it, he hated everything about the color blue. Blue was the color of Giyu Tomioka.

Giyu doesn't know if he has a soulmate, but even so, he still loves to doodle all over his arms in the hopes maybe there's someone on the other side. So when the silence is replaced by red ink and a sweet unfamiliar tingle, he can't help but find himself falling in love with the stranger who's supposed to be his fated partner