>>3705271I would say don't mind the fandom too much, Vocaloid is so old at this point that fans are overall very chill (aside from the zoomers who recently got into it because of Project Sekai, but we don't talk about them). Len in particular has a very rabid fandom of thirsty tween girls but they're easy to ignore.
About mothy's songs specifically, they're all part of a huge series that spans like dozens of songs or so, there's probably a list on a wiki somewhere covering all of them. It's one of the biggest Vocaloid story projects that have been made, I believe