The Kinrō Kanshasai 2015 event announced that a second Garo anime season and movie is in production. Aswell as 3 new live action movies, a new live action series, manga series and a musical. Date and further details have not been revealed.
It seems that the movies, anime, live-action and musical are all adapting a different part of the Garo story, I myself don´t know anything about it apart from the banging anime that we´re treated to this season, but according to wiki the series is considered by some to be a turning point in tokusatsu entertainment, as it was marketed towards adults and older teenagers as opposed to younger children. The show contains graphic violence, nudity, and mature themes. It was marketed as a “Hyper Midnight Action Drama” and the success of the first series lead to a franchise which has had several films and subsequent seasons over the year.