Sorin (Japanese: ヒサシ Hisashi) and Luno (Japanese: ツキヤ Tsukiya) are characters of the day who appeared as silhouettes in a flashback and on a painting in Night and Day, You are the Ones!.
Sorin and Luno were brothers who lived in Johto a long time ago. At one point, Sorin was appointed the title of liege of Eclipse Castle. As Sorin was giving a speech to a crowd of people at the castle during the Eclipse Festival, he was attacked by his younger brother Luno, who tried to dethrone Sorin and take over the castle. Sorin's Espeon and Umbreon managed to protect their Trainer however, and the castle was saved. To celebrate their bravery, Sorin made a crest engraved in the castle honoring his two Pokémon.
The failure of his coup ashamed Luno, after which he and his family decided to go into hiding. Many generations later, Sorin and Luno both had descendants continuing their legacies. Sorin's descendants Helia and Soleil were the new lieges of Eclipse Castle, while Luno's descendant Ilunas still lived with the shame of his ancestor and tried to prevent Soleil from becoming the new liege. After a Pokémon battle, Helia and Soleil recognized Ilunas as the descendant of Luno and convinced him to change his ways, after which Soleil was able to become the new liege of Eclipse Castle.