After working in the backing bands for singers such as Yosui Inoue, Misato Watanabe, and Anri, he came into prominence as a musical collaborator for the Southern All Stars frontman Keisuke Kuwata's eponymous 1988 solo album.
Although his own leader albums failed to receive public attention, Kobayashi garnered commercial success in collaboration as producer or songwriter with other artists.
The producer and the band have gone on to record together to date, achieving mainstream success with cumulative sales of over 58 million copies albums and singles as of March 2013.
[2] In 1995, Kobayashi formed another multi-million selling pop group My Little Lover fronted by his then-girlfriend and first spouse Akko, and remained as a full-time member of the band until the couple's marriage broke up in the mid 2000s.
Along with Grammy-winning producer Ryuichi Sakamoto and Mr.Children's chief singer-songwriter Kazutoshi Sakurai, he established a non-profit organization called AP Bank in 2003.