Petite and youthful, Nemu has green eyes and black hair with slightly parted bangs and is pulled back into a long braid. Her expression is almost always melancholic, and it is rare to see her smile or show any real joy in her distinctive green eyes. Her uniform consists of a short black kimono with a white nagajuban under it. The sleeves of her kimono are not as wide as those worn by most Shinigami and the upper parts of the sleeves are puffed. She wears a traditional wide white obi with a red cord fastening it. On her left sleeve is her lieutenant's armband. In addition she wears white gloves that cover only the back of her hands and wrists; as well as a dark red choker.
Due to the fact that she was abused and mistreated in every possible way by her "father/creator," Mayuri, Nemu is a very shy, withdrawn, and introverted individual, preferring to stay silent in her captain's presence. Despite Mayuri's seemingly lack of care for her existence she is very loyal to him, to the point of willing to badly injure herself just to give him an advantage in battle.Unlike her "father," however, she seems to have compassion for others, saving Uryū Ishida's life as a thanks for not killing Mayuri.
Being the daughter of Mayuri, they share several similar traits. One such trait is their food preference. Nemu, just like her father, likes pike fish, and dislikes onion. Other similarities are their interest in Human experimentation and their main free-time activity, which is reading every single character published in Seireitei Communication.
It is also known that Nemu is being considered to be the next vice-president of the Shinigami Women's Association, supposedly because she carries out President Yachiru Kusajishi's orders just as faithfully as the ones of her father. Such orders included building hidden tunnels and a hide-out on the Kuchiki grounds for the members of the association to use. Surprisingly, Nemu shows great joy at the prospect, making it one of the few, if not only, times in the series she has shown actual emotion.
Little else is known about Nemu outside of the fact she is the artificially created "daughter" of Mayuri Kurotsuchi. He seems to have used a combination of Gigai and Artificial soul technologies to bring her to existence. While she is partly resistant to poisons she is still affected by Mayuri's Zanpakutō, though it is non-fatal to her.
In an omake, it is revealed that when taking photographs, Nemu says "butter" instead of "cheese."