Moribito Series

Once every 100 years, a water spirit implants an egg into a person who then becomes the Nyunga Ro Chaga, the Guardian of the Spirit. This time, the Guardian of the Spirit is Chagum, the second prince of the New Yogo Empire. However, Chagum's father, the Mikado, believes the Spirit to be a demon, and to protect the reputation of the royal family he attempts to have Chagum killed. Fearing for her son's life, the Second Queen, Chagum's mother, hires Balsa, a female bodyguard, to protect him. And the Mikado's assassins aren't the only threat Balsa and Chagum face: there is also Rarunga, the Egg-Eater, a being from the spirit world, which killed the previous Guardian. Balsa must enlist her childhood friend Tanda, a healer; a powerful shaman, Torogai; and the young star reader Shuga to help her protect the prince. (Source: Manga Updates)