Showing The Gatekeeper's Son by C.R. Fladmark

Junya’s grandfather is a billionaire who keeps the secret to his success hidden in a heavily guarded safe.
His mother is a martial artist who wields a razor-sharp katana—and seems to read his mind.
And a mysterious girl in a Japanese school uniform can knock him over—literally—with just a look.
What do they know that he doesn’t?
Junya’s life takes a dangerous turn on his sixteenth birthday, when someone sets out to destroy not only the family’s business empire—the one that he’s set to inherit—but Junya himself. He’s fighting for his life, and doesn’t know who to trust.
What has his family been keeping from him?
Junya’s journey takes him from the narrow streets of San Francisco to Japan, and through hidden portals to the top of the ancient Japanese Izumo Shinto shrine, to places where death and violence are a way of life. And in a mystical world he’s never imagined, he finds his true destiny.