At the end of the game in the credits it says the game is based on a book দ্বারা some japanese guy. i found the book but it was only written in japanese. is there an english version witten?

Well, this is Square Enix! I have to say, I প্রণয় them with all my heart, but they are notorious for cheaping আপনি out! I dont believe there would be an English version, but checking one আরো time doesnt hurt.