Mima Yukito

Yukito lost his parents and lost sight of his little sister because of a natural disaster. He was placed in an orphanage with Chimari, who also lost all her family. Over the years, they develop a brother/sister like relationship. He returned to his hometown after 15 years of absence to find his biological little sister.

As soon as he arrives in his hometown, Yukito realizes he has lost his wallet. He begins to look everywhere and is approached by a very pretty girl. Very shy, she is surprised by Yukito and tries somehow to ask if the wallet she found on the floor is that of Yukito. Yukito thanks her and she answers him that that she also loses things, then, they separate.

Yukito then finds a wallet on the ground and sees by the identity card that it is that of the girl. After some search time, he found her and he returned her wallet.

This is how he meets Miyuki and learns that she has also returned to the city to find her older brother and begin their adventure.

"Mima" ( 美馬 ) isn't his real last name, it's the orphanage who give this one to him and Chimari.

Spoiler

His true name is Kamishina ( 神志那 ) Yukito ( 幸人 ).