Matti Salo (born 1980), professionally known as Asa and previously as Avain, is a Finnish rapper, record producer and singer.

Under his initial stage name Avain, he released his debut album Punainen tiili (The Red Brick) in 2001.

Soon after its release, Salo parted ways with his record company and went on a few years hiatus.

[1][2] While the rights to his former stage name remained at Warner Music, Salo emerged in 2004 with his current alias Asa.

[3] In 2006, Asa was fined for possession of marijuana, cocaine and hash.