Trying to contact estate of Shinobu Hashimoto

Hello, I am trying to contact either the estate or a representative of Shinobu Hashimoto. I would like to inquire about the possibility of adapting one of his screenplays for the stage. If anyone has any leads or idea who I might contact, I would be extremely grateful.
Thank you-

Sorry about the late reaction to this, OldPineTree! Have you tried contacting the publisher of Hashimoto’s book, Compound Cinematics? And if the screenplay was filmed, the producing film studio might also be able to help.