Mudpit

Mudpit follows the adventures of four teens who form the eponymous band, Mudpit, as they try to earn a recording contract through competing in the Japanese massively multiplayer online role-playing game Muzika.
Each episode in the series consists of a challenge proposed by Slime, and the band's attempts to win the challenge; during this one of the band members learns an important life lesson. Each episode concludes with an original song sung by the band members. (official distributor synopsis)