Even mermaids can have disconnected legs and butts apparently
Have you done Shin Megami Tensei IV Mermaid yet? https://megamitensei.fandom.com/wiki/Mermaid
I have no idea what is going on from her waist down, which is a weird thing to say about a mermaid.
She's actually a creature with 3 legs, we just can't see the other one that's attached to her far hip, and she's pretending to be a mermaid but she hasn't fully pulled her fake fishtail up yet.