Seirei no Moribito  

Guardian of the Sacred Spirit, 精霊の守り人

Every 100 years, a Water Fairy lays an egg inside someone who becomes the Guardian of Fairies. This time around, it's Chagum, the second prince of New Yogo Kingdom. Life isn't easy for Chagum; his father, the king, sees him as an inconvenience and tries to have him killed. To protect him, the queen sends Balsa, a female guard, to keep him safe. However, there are beings from another world called Nayugu who constantly attack Chagum in order to eat the egg that he carries inside his body.