‘Lord of Lords Ryu Knight’

In the fantasy world of Adeus Legend, knights, priests, magicians, ninjas all summon Giant Mechs with ability similar to their class to fight. This is a story about the growth and learning of a young knight. He starts out his adventure with an older knight mentor who has a mysterious past, then saves a princess and her priest companion and goes on a quest to reclaim her kingdom.

Descriptions taken from AniDB.net