The nude celebrity subreddit had an adult video of someone named Kaito Daiki Diver. But there is no diver with that name. The closest I could find was Japanese swimmer Daiyo Seto.
There is no Kaito Daiki Diver actor, singer, or any other celebrity.
But there's a character named Kaito Daiki in the Kamen Rider franchise.
Created by Shotaro Ishimori in 1971, the Kamen Riders are tokusatsu, special-effect powered superheroes like the Power Rangers. Motorcycle-riding loners (until they team up), they wear special belts that transform them into masked, muscled, insect-motif beings.
In the tv series Kamen Rider Decade (2009),Tsukasa Kadoya (Masahiro Inoue) must travel through the nine universes to fight space-time anomalies. He encounters Daiki Kaito (Kimito Totani, left), a charming interdimensional thief who eventually reforms and becomes Kamen Rider Diend (named after his home world).
In an interview, Kimito stated that the guys are involved in a romance, but I think it's subtext rather than text.
Ryota Murai (left) plays Kamen Kuunga. Dozens of actors have played Kamen Riders, but this is the only guy I could find with nude photos.
Except for the adult video. But first I have to research Kimito Totani.
Born in Tokyo in 1990, Kimito broke into on-screen acting with the martial arts movie Tsubaki Sanjûrô (2007) and a 2008 episode of the teen angst drama Gokusen. But Kamen Rider sealed his career: he went on to play Daiki Kaito in twelve tv series, animes, and video games. His most recent Kamen Riders are:
Kamen Rider Zi-O (2018): Sougu Tokawa (So Okuno) wants to become king, so he transforms into the titular Kamen Rider, but this has the side effect of collapsing the universe.
Kamen Rider Zi-O Next Time: Geiz, Majesty (2020): In an alternate universe, some high schoolers try to achieve their dreams by Kamen Riders. So Okuno is still trying to become king.
Kamen Rider Outsiders (2023): a cross-over anthology series.
Presumably he's played the character as gay throughout.
Shots from the video after the break