"Monster" (モンスター, Monsutā) is Pink Lady's eighth single release, and their seventh number-one hit on the Oricon charts in Japan. The single sold 1,600,000 copies, and was number one for eight weeks. It also peaked at number-one on the Japanese Music Labo chart. According to Oricon, this was the third best selling single from 1978. "Catch Lip", the B-side song, was used for commercials promoting Snow Brand's Hōseki-bako ice cream. The song was performed on Pink Lady and Jeff along with "UFO," making those two the only Pink Lady songs to be performed on the show.