Nekoin has the appearance of a pink cat-shaped coin with a cat face on both sides. She has two dark red eyes and little violet eyelashes that stick out a little when viewed from the side.
She is constantly on the move and spins around quickly. It's hard to catch her because she is so fast. That's why using the Stoplight or the Bicycle when trying to catch her is recommended. She shows a normal reaction to the Cat and the Knife Effects as well.
- She is the only Yume Nikki character on the front page of Kikiyama's website other than Madotsuki herself.
- The Cat Effect references the Maneki-neko figure, a Japanese talisman supposed to bring good luck and fortune. Nekoin's appearance resembling a coin ties into this, as not only were Maneki-neko often depicted holding a gold coin, but they were also used as coin banks much like a piggy bank. On top of that, tiny coin offerings were sometimes left near the figures as a request for good luck, fortune or for wish fulfillment.
- A spinning coin may also be a reference to the spinning coins of the Super Mario series.
- The cute and simple design and her general shape may also be inspired by the popular Sanrio mascots, such as Hello Kitty. This is furthermore in tune with Nekoin's theme, as Hello Kitty resembles the Maneki-Neko and was supposedly inspired by the figure.