Saiyuuki

Saiyuuki or Journey to the West is one of the four great books of China. Sanzo Hoshi and Son Goku to go on a journey to examine Buddhist scriptures. Sanzo Hoshi gets caught by a monster and carried to the top of the mountain. Son Goku sets off to rescue his friend. He will need to defeat numerous monsters and pass through three demon gates.

[From vndbreview]