Matti Johannes Koivu is a Finnish musician. His first solo album Puuhastellen was released in 2006. Before that he was the vocalist of Ultramariini. Koivu's music has been said to take a lot of influence from folk and beat music. His probably most popular album is Irwin Goodmanin Lauluja (2008) which is a cover album of the songs of another Finnish musician, the legendary Irwin Goodman.