Takt of Magic is a spiritual successor to the Nintendo DS game Lost Magic. Since Takt is complete Garakuta Studio might be working on a true sequel to Lost Magic.
A trademark found in Japan’s trademark database suggests one is in development. Taito registered the rights to Lost Magic: Shouryu no Kyousoukyoku (loosely Lost Magic: Concerto for the Fallen). The first game didn’t have a subtitle so this discovery appears to be a new entry in the Lost Magic series.