Motobu, Okinawa (2004 – 2009) Hearts Grow (ハーツ・グロウ), was a Japanese pop/rock band. The band formed in 2004 and debuted as an indie band in 2005. After the release of two indie mini-albums the band signed to the major label Epic Records Japan in 2006. However the band officially disbanded a year after the release of their single "Sora" (theme song to Tetsuwan Birdy DECODE). Information: Before Hearts Grow formed, the band was divided into two bands.