SatouSai

SatouSai is the slash ship between Satou Hiroshi and Saiki Kusuo from the Disastous Life of Saiki K fandom.

Canon
Even though Saiki and Satoru don't interact, they still have their moments together.

Saiki admired Satou for how normal he was, claiming he wanted to live a life just like him, Saiki became so intersted in seeing all the normal/average events that would happen in Satous life that he would start watching him and seeing his actions during the school day or after school was over, studying his actions and would act with excitement whenever Satou did something that was average. Also notable that whenever Saiki was admiring Satou he would smile even though he's a character who keeps a serious face for the most part.

Saiki claims he respects Satou the most in his school. He would get mad at someone who tried to disturb Satou's "ordinary life" he wanted Satou to stay the way he was. But sometimes Saiki would let the situation play out and Satou would deal with the situation as average as ever, much to Saiki's excitement. Saiki even tried becoming friends with Satou once, which didn't turn out so well, but Saiki still continued to admire Satou.

Fanon
The ship first started due to how Saiki reacted around Satou, saying how he respected Satou, how he would follow him around, and how he would be amazed by mostly anything he did.

The ship is popular to a few, but is mostly put to the side due to other famous ships, since this fandom doesn't have that many ships or is most likely due to how Satou is a forgettable character due to how average he is. But people in the fandom still acknowledge that Saiki might have some kind of feelings for Satou.

Fandom

 * Saiki x Satou tag on AO3
 * SatouSai stories on Wattpad

Trivia
Saiki wants to be an average student like Satou, while Satou on the other hand doesn't want to be so average, like Saiki.