As Hideki Motosuwa heads out of his place, he unintentionally leaves behind his wallet. Chii seizes the opportunity and picks up the wallet, trailing Hideki. Meanwhile, Sumomo and Kotoko are left behind at the apartment. Soon, Sumomo realizes that Chii has forgotten her undergarments. Thus, Sumomo and Kotoko embark on an exciting journey to return the panties to Chii.