She is a very calm and patient person, a girl who constantly loves to drink tea, if it is in school or in a restaurant. She is not always that calm and patient as she can sometimes be rude, angry or jealous, even when some girls are starting to flirt with Haruyuki. She is also a girl who is wise with words and can talk manipulatively to another which they see it as annoyance. She is also a smart and clever girl, knowing the details about the "Brain Burst" game, since she was once known as the "Black King". The Brain Burst is not her only knowledge. She also has knowledge about wired connections or anything network related, as she can tell and give information in the smallest details. She even knows the steps of the networks that has been used.
Kuroyukihime thinks highly of herself also as a very intelligent person. At the time that she was called "Black King" she killed the previous "Red King" and also tried to kill the other members of the "The Six Kings of Pure Color" to become level 10 and find out who the creator of the Brain Burst game is. When she doesn't know someone's name, she will address them as "boy" or "girl", as she did with Haruyuki constantly when the two met and afterwards. She seems to be extremely skilled in playing simulation or any types of games, knowing that she defeated Haru in his own game by achieving more points then him. She also loves Haruyuki and their friendship starts to grow more to the point where she is pretending to be his wife. However, even that they show romantic feelings to each other, in the Brain Burst world, they become serious in fighting against others or giving each other information, but will change if someone tries to flirt with Haruyuki.