Secret (Korean: 시크릿; Japanese: シークレット, often stylized as SECRET) is a South Korean K-pop girl group formed by TS Entertainment in 2009. Consisting of four members—Jeon Hyosung, Jung Hana, Song Jieun and Han Sunhwa—the group released their third Japanese single and first Japanese digital single, "Twinkle Twinkle". The tittle track was used as ending theme song for the anime Rock Lee no Seishun Full-Power Ninden.