When Mina agrees to come as a last-minute invitee to a mixer, she is surprised to see her brother sitting across the table. However, she decides to bite her tongue and not reveal this to her peers—even when the king's game that they are playing starts to get increasingly sexual.

Elsewhere, the nature of Sayaka and her brother's relationship changes when her brother discovers a hole at waist-level in the wall between their rooms. Will Sayaka notice her brother watching her most intimate moments?

[Written by MAL Rewrite]