楽しい音楽 (Tanoshī Ongaku) were a duo likely consisting of instrumentalist 吉川洋一郎 (Yoichiro Yoshikawa) and noted folk pop singer あがた森魚 (Morio Agata), however this cannot be entirely verified as the project has faded into obscurity over the years and relatively little is known about the band.
They only ever put out one 11-track album in 1983 titled "やっぱり". Their music is fun and full of synths and childlike strangeness, similar to that of Picky Picnic.

楽しい音楽 on Last.fm.