Christel Martina Sundberg (born January 3, 1982, Helsinki), known by her stage name Chisu (Finnish pronunciation: [ˈkisu]), is a Finnish pop artist, songwriter, and producer. She wrote her first single, Mun koti ei oo täällä, to the soundtrack of the movie Sooloilua. The song was a hit in Finland in Spring 2008, peaking at number one on both the Singles Chart and the Downloads Chart and spending seven and nine weeks atop, respectively. She released her second album Vapaa ja yksin on September 23, 2009. Her third album, Kun valaistun, was released on October 5, 2011, through Warner Music Finland. Another version of the album, entitled Kun valaistun 2.0 was released on June 6, 2012. Her fourth and latest album, Polaris was released on October 2, 2015.
Chisu has also written songs for Antti Tuisku, Tarja Turunen, Jippu, Kristiina Brask and Kristiina Wheeler. During her career, Chisu has sold over 230,000 certified records, which places her among the top 80 best-selling artists in Finland.
In November 2012, Chisu was connected to a copyright controversy in Finland when a nine-year-old girl's home was raided by the police and had her laptop confiscated due to allegedly downloading Chisu songs. The controversy was named as Chisugate by media. It has been alleged that the files the little girl downloaded and later shared, were bogus files disguised as the Chisu album and therefore she did not actually share Chisu's music.
Christel "Chisu" (äännetään "kisu") Martina Sundberg (s. 3. tammikuuta 1982 Helsinki) on suomalainen muusikko.
Chisun ensimmäinen soolosingle oli Sooloilua-elokuvan tunnuskappale "Mun koti ei oo täällä". Se nousi sekä Suomen single- että latauslistan kärkeen alkuvuodesta 2008.