Kuroneko, as her name implies, is a black cat. Yasuhiro Nightow has confirmed that the cat is female. Kuroneko-sama is a petite black cat with large green eyes, and little is known about her personality, though she behaves like an ordinary feline.
She appears in every episode of the first anime series and sporadically in the manga, often serving as a running gag by popping onto the screen at opportune moments and simply saying "nyaa." Despite her frequent appearances, Kuroneko-sama has few instances of plot significance. She prevented Wolfwood from cheating in a chess game during the episode "Escape from Pain" (and also replaced Vash briefly in "Hang Fire"). Nightow has mentioned that she is just something easy and calming to draw between action scenes. His typical response to questions about her nature or significance at anime conventions is "Kuroneko-sama is a small black cat."
In Trigun Maximum, Kuroneko only appears in Nightow's commentary at the end of each issue, often criticizing the author's lazy and silly tendencies.
In Trigun Badlands Rumble, Kuroneko can first be seen napping at the newsstand where Vash learns he is blamed for Gasback's bank heist. The cat is seen again watching Meryl and Milly discuss their situation with Cain's statue. Additionally, during a bar fight later in the film, Kuroneko flies through the air along with many other items, seemingly thrown by someone as a projectile.
Kuroneko-sama also makes a brief cameo appearance in some episodes of Kekkai Sensen and Kekkai Sensen & Beyond.
