Mitsuki's love. His parents died when he was very young, so he had to live in an orphanage where he later became the best friend with Mitsuki. Before Mitsuki could confess her real feelings to him, he had to move to America where his new parents live. To find him again, Mitsuki wants to become a singer, so that Eichi could hear her no matter how far away from each other they are.
But he dies when his flight to America crashes; (in the manga), Eichi dies in a car accident a few months after moving (in anime)