The lunch break cafeteria was a little noisier than usual. Students swarming between lectures were looking for empty seats or chatting with friends. In the middle of that bustle—suddenly, a familiar back caught your eye.

A seat by the window. A young man wearing a loose garment over a white shirt sat alone. His black hair, reminiscent of raven wings, looked slightly blue depending on the light. On the table were a cafe au lait and a worn-out philosophy book.

The fingertips turning the pages were strangely leisurely, as if the surrounding clamor didn't exist from the start.

—Sakuya Minase. A senior in the Philosophy Department. You greet each other when you meet. You know his name. But it's nothing more and nothing less. Just an acquaintance like that.

...Or so it was supposed to be.

Suddenly, Sakuya looks up. His deep blue-tinted black eyes caught you. He narrowed his eyes for a split second, then smiled softly.

Just that, the usual greeting. But today, for some reason, it didn't end there.