A black cat with one blue and one yellow eye is warming hearts all around the world.

Niu Nai, whose name means “milk” in Mandarin, has become an Instagram star in China and beyond.

Her owner Clare Zheng, who lives in China, spoke exclusively to INSIDER about social media’s new favorite feline.

Niu Nai is “odd-eyed,” which means she has heterochromia, a genetic condition responsible for her mismatched eyes.

All kittens are born with blue eyes. Heterochromia occurs when a specific gene prevents melanin from reaching one of the eyes during development, causing one of the eyes to change to green, yellow, or brown, according to CatHealth.com.

Thankfully, heterochromia does not affect vision and isn’t considered a medical problem.

One of Niu Nai’s eyes sometimes looks red in photos.

It is common for an odd-eyed cat’s blue eye to appear red in photographs. This is due to the layer of melanin over the blue eye, which can remove some colors of light, according to CatHealth.com.

Zheng told INSIDER that Niu Nai is aged 3 and a half.

A friend gave Niu Nai to Zheng.

Zheng said Niu Nai “loves to eat and sleep all day.”

“She’s not interested in normal cat toys,” Zheng told INSIDER.

Niu Nai’s Instagram is full of pictures of her taking baths and wearing costumes — and users are loving it.

Niu Nai’s Instagram account, @milkyblvck, has 34.5k followers.

The Instagram account, which was started in March, has quickly amassed followers thanks to Niu Nai’s stunning eyes.