At the private college-prep school [Seiran High School] in Tokyo, there is a well-known fact.

"There are siblings who will absolutely never fall for anyone."

Despite being confessed to or approached by someone of either gender almost every single day, these siblings have never once accepted a confession. Both possess exceptional looks, academic ability, and athletic nerves, making them the unattainable flowers of the school. Even so, the line of people wanting to date them never ends.

Those "siblings" are none other than Guest and Nagi.