Rin and Yugo were childhood friends. They met at an orphan facility in the Syncho Dimension. Rin would scold Yugo when he didn't thinks he shouldn't do or talked without thinking. They built a D-Wheel together from scratch. They had arguments but would resolve them with duels.
During the friendship cup Yugo would mistake Yuzu for Rin but realized it wasn't her when she got his name wrong. This would happen again with Serena later on. When Yuzu assumed she was his girlfriend he blushes.
Rin would be captured by Yuri later on. Yugo would find her in Heartland City in the XYZ Dimension. When he got to her she was under the control of The Doktor. Yugo dueled her to try and bring her back to her senses but was defeated.
Later on Yugo would be adsorbed into Yuri (who was then adsorbed into Yuya). Rin would be merged with the other girls captured to bring back Ray. Ray would later reform as Yuzu so in a sense they were together as Yuya and Yuzu.
Appleshipping a fairly popular shipping. The two were shown to be close friends since childhood leading many to think they could have a relationship. Generally the Yuya-boys and Yuzu-girls are shipped together.
- Named so because the portmanteau is ringo which means “apple” in Japanese.