He's a humanoid black cat, with dark brown hair and blue eyes. He is well-dressed mainly in brown and wears white gloves.
He's a smart cat knowing a lot of things, and is very mild, proper and formal when he is on his main job, but he is quite strict when it comes to his work hours.
He hates kids and is fond of money when it's not part of his main job, and would act slyly to get what he wants.
Kurosu is a powerful level six black cat who dutifully works for his young master, going so far as to do most of his work when he is incapable of doing things for himself, and essentially serves as a valet. His contracted working hours are from 9am to 5pm, and he promptly stops what he is doing when it is time to clock-out, insisting that he never works overtime.
As he is fond of money, he would seize any opportunity, even stealing from his master and going against him during his non-working hours, and accept any payment for a request.
He served as chief invigilator for the Black Cat Kids Party.
He hosted the Black Cat Secret Meeting. With no knowledge of its purpose, he agreed with Oboro to conduct it as a protest rally against the Shinigamis until the real purpose is discovered. He would wear a respirator mask to avoid collapsing in disgust like everybody else when the winning prize is revealed, but would be unmasked by Suzu going unconsciously mad.
In his final appearance, he takes pleasure of informing his master the rumor that his crush Ichigo has a boyfriend coming to play at her home, which got Shoma shocked, although it's actually her husband Sabato from her previous life and she can't start over with him due to their age difference.
AbilitiesDue to his high skill level, he is able to use genjutsu, illusory black magic that aids him in his work. He uses a wand in the shape of a black cat's paw that helps him conjure these illusions and aid him in corralling fallen spirits.
Privately, Kurosu finds working for his spoiled child master irritating, but he is too professional to ever express this sentiment aloud, although he would do anything against him when he has the chance.
At some occasions, they are at odds to get a reward.
- “If I spend a whole day with him, I’d beat him up.” (一日一緒にいるとぶっとばしてしまいそうです) - Chapter 104, thinking about Shoma who paints his face
- His voice actor had provided the voice of Yutaro Yudono from Ranma 1/2 and Amari Nobunaga from Inuyasha.