Note, Twin Tail doesn't literally have 2 tails, she just has the two-tone hair of her tail in a split ponytail. "Twintail" is an alternate term for "pigtail", and seems to show up more frequently in reference to anime characters. Specifically (sorta), pigtails as a hair style is a type of twintail style, which tends to be shorter found on children on opposite sides of the head, while twintails are more general but typically very long. I didn't realize twin tails was a literal thing, but for the distinction, the OC is named "Twin Tail".
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For those who prefer following my other art, I'm sorry. This was something I've been meaning to get through for over 3 years, and I'd like to, at the very least, prove to myself that I can finish something that I started. So I'll be trying to focus this down.