These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: School Mermaid
Fridge Logic — Suppose that a girl named Hanako is in love with a boy named Tarou. Tarou had the surname Suzuki until two weeks ago, when his mother divorced and took custody of Tarou. His surname was thus legally changed to his mother's maiden name, Watanabe — although he's still listed in the school's records as Tarou Suzuki. If Hanako decides to win Tarou's love by eating a mermaid, does she eat a W or S mermaid?
Maybe the spell requires names that were given by birth.