Chou Tzu-yu (Chinese: 周子瑜; Pe̍h-ōe-jī: Chiu Chú-jû; born June 14, 1999), known mononymously as Tzuyu (Korean: 쯔위, Korean pronunciation: [t͈sɯ.ɥi]), is a Taiwanese singer based in South Korea. She is a member of the South Korean girl group Twice, formed by JYP Entertainment in 2015.