|This article is about a/an ally in Kamen Rider Den-O.|
"Yu" is the ten-year old version of Yuto Sakurai (桜井 侑斗 Sakurai Yūto) that the Den-Liner crew met during the events of Cho Kamen Rider Den-O & Decade Neo Generations: The Onigashima Warship, nicknamed "Yu" and unaware of his true identity.
After Yuto disappears in time, an even younger version of Yuto appears known only as "Yu". Yu possesses an artifact that the Oni Brothers Goludora and Shilubara need to complete their plan. Thus Ryotaro, Kotaro and the rest of the Den-Liner crew aid him and get the artifact to the past. To protect Yu, Deneb, not knowing he is actually Yuto, asks to form a contract with him, allowing him to gain a physical form. Yu's wish for the contract is for Deneb to see his contract holder, once more. The adult Sakurai and the ZeroLiner make a cameo appearance in the end, with the former reuniting with Deneb.
Behind the scenes
As a child, Yuto Sakurai is portrayed by Ruka Sawaki (沢木 ルカ Sawaki Ruka), who is actually a girl.
- In episode 39 of Kamen Rider Den-O, "The Rider Disappears As Well", Yuto is seen as a high school student with his classmates and teacher in 1993. However, during "Cho Kamen Rider Den-O & Decade Neo Generations: The Onigashima Warship", which is set in 1980, Yuto was at least ten or eleven years old. No explanation is ever given for the discrepancy.