They're the mascot for #SharkeyWorld, an instance powered by @Sharkey (cc: @ruud). It's a community of roughly ~120 members, and part of the rapidly growing squad of instances based on this #Misskey fork. #OhHaai
Haai is also the Dutch word for shark, and also is a homophone for a greeting (Hi!).
I've changed sharkey.world's branding; @vsp has created some nice images and our new mascot: Haai
Thanks for the cool images, Vincent!
I'll check if I have uploaded all the right images in the right places. Also I'll try to figure out how to change the site's theme (colors) to match the images.