Catgirl

Catgirls, also known as Nekos  (ネコ, cat in Japanese), are an intelligent species of cat-human hybrids that live alongside humans in the Nekopara series. Catgirls physically resemble humans with feline ears the same color as their hair, slitted pupils, a tail, and a cat-like mouth.

Catgirls were once left homeless and living in the streets, but now they are domesticated by humans and aren't allowed to go anywhere by themselves without their masters unless they have a bell.

Diet
Unlike real-world cats which are true carnivores, catgirls appear to be omnivorous as the Minaduki catgirls have been shown eating various foods throughout the visual novels, including sweets and tea. A running gag throughout the VNs is their preference for fatty tuna.

Behaviour
Generally catgirls can behave much the same as humans. They have the ability to learn, communicate and have complex emotions. Maple for example is shown having experience with emoticon texting, and began learning the guitar in Vol 3. She also initially disliked the phrase "catgirl" since she felt that people didn't view her as an individual.

Being based on cats and having cat-like traits means that younger catgirls are often prone to some of the habits of regular cats, including the desire to hunt small objects, tails sticking up when happy, and giving in to temptations of food. They can be taught to ignore these desires to some degree, as shown when the Minaduki catgirls tried (and mostly failed) to show their restraint as a result of getting their bells.

Romantically, catgirls are stated to be more honest about their feelings. However this does not always seem to be the case, since Azuki typically is not.

Vanilla and Chocola have demonstrated the ability to detect scent changes, especially when going into heat.

Development
In general catgirls mature much faster than humans, reaching sexual maturity at around a year - the youngest so far being Chocola and Vanilla at 9 months old, with all the other catgirls having been stated by Shigure to have gone into heat before Vol 1 and working it off with excercise. Likely because of their rapid growth, they must pass a social skills test to earn their bells and their independence - although Cinnamon states only 1 in 10 catgirls ever pass.

It can be assumed individual catgirls of the same breed develop differently like humans, though it has been shown that there are clear differences between breeds. For example, Coconut is a Maine Coon at 1 year old, while Azuki is a Munchkin at 3 years old, with the former appearing much older than the latter in both body shape and build.

Catpanionship
In the Nekopara universe, relationships between a human and a catgirl are not uncommon, and a catgirl in such a relationship is referred to as a "catpanion". Catgirls cannot produce offspring with humans, though their physical similarities with humans mean they are still capable of intercourse.

The Minaduki catgirls in particular seem to have no qualms against being in a polyamorous relationship with Kashou, so long as they receive adequate attention.

Known Nekos

 * Chocola - The youngest (together with Vanilla) of the nekos and is Vanilla's biological twin. She has developed a close attachment to Kashou and couldn't bear to be separated from him. Her cat breed is unknown.
 * Vanilla - Chocola's biological twin and has a very close relationship with her. Vanilla rarely expresses her true emotions and has a kūdere-type and stoic personality. Her cat breed is unknown.
 * Azuki - Eldest and shortest of the Minazuki's nekos. She has a mischievous and energetic personality and oftenly picks fights with the others. She is a Munchkin Cat.
 * Maple - The second eldest of the nekos. She is well-informed about technology and enjoys visiting various shops and restaurants to try different foods and drinks. She is an American Curl.
 * Cinnamon - The third youngest of the nekos. She often interprets and expresses everything in a sexual manner, resulting her to be aroused. She has a very perverted personality. She is a Scottish Fold.
 * Coconut - The second youngest of the nekos. She possesses a very womanly body though she isn't confident about this and instead, yearns to be called cute. She has a cool personality according to the others. She also appears to have very low self-esteem, and tends to think about things such as suicide when she fails to do something or doesn't meet the standards of others. She is a Maine Coon.
 * Milk (also known as Food Stand Cat) - A catgirl who manages a takoyaki food stand situated in the park where Kashou, Chocola and Vanilla often visit at during their break hours. She has a similar personality with Chocola, being cheerful and friendly even to new acquaintances. Her cat breed is unknown.

Trivia

 * According to a Q&A question in the Kickstarter for the Anime OVA, Catboys do exist.
 * All of the catgirls shown so far always have hair covering where their human ears would be.