Manga Sayonara No Asa Ni Yakusoku No Hana Wo Kazarou

Maquia is standing at the beginning of the story. She's a representative of the family in which the members stop aging after they are mid-teens. Despite she doesn't have parents, her life seems to be peaceful. But the girl feels lonely.
This peaceful life is destroyed after the army invasion. They are looking for the secret to human immortality. The most beautiful lady of the clan was Leilia. She's stolen while Maquia is secretly falling in love with her. Maquia manages to run away but she loses her home and her friends. When she was wandering in the wood all alone, she meets Erial, a baby boy without parents. Erial is getting older while |Maquis stays at the same age. How will it affect their relationship?