TOHO owns the Distribution rights for Gamera......or at least did as of 10/03......I don't know if they had a contract for any new Gamera film that may be made or produced in the future, or only for the trilogy, or maybe only for G3 or if they did, if they renewed it.......
Kadokawa Daiei Studios or films or whatever they've decided to call themselves now, owns the Gamera license.