>>97501079San comes from an april fools stream Sana, and her genmates did. As San, Sana made a joke that he had a "huge rocket". Which I think is why he was used in so much nsfw fanart. He is also just a nice design. I don't think there's a shota in any EN vtuber corpo, so corpo shotacons are kinda starved for content too, which can also explain his popularity.
