While searching for a birthday present for Tatsuno, Hotori visits clumsy Shizuka Kameidö's antiques store. Shizuka offers Hotori an African mask that grants the wearer the ability to locate anyone and anything (including lovers). At Tatsuno's early birthday party, Hotori presents her gift: a strange locked box, missing its key. Hotori tries to discover everyone else's birth-dates, but Futaba changes the subject each time she's asked. When Hotori extracts Futaba's student ID card from her bag, she discovers that today is also her birthday, causing much consternation...