Atsushi has silver hair, pale skin and yellow eyes with a violet tint. He has short hair on the right side of his face and long hair on the left side with a noticeable black stripe. He is of average height and thin build. At first, he wore clothes from the shelter: a gray sweater and pants, black pumps. After joining the Armed Detective Agency, he began to wear a white shirt with elbow-length sleeves, a black tie, black pants, boots, fingerless gloves, suspenders, and a belt combined with a long belt that dangled loosely from the buckle. When he partially transforms into a tiger, his eyes become like a tiger's eye and he has tiger stripes. If completely, then his limbs turn into the limbs of a tiger, and a tail appears. Due to the abuse at the orphanage, Atsushi is not at all confident in himself, and even hates himself. He is obsessed with the past and has made many bad decisions throughout history due to his low self-esteem. The agency greatly influenced Atsushi, breaking his past life foundations. He was shocked that there were people in the world who needed him. Therefore, in moments of danger, Atsushi is willing to take risks for the sake of others. Due to the fact that the young man grew up in an environment of humiliation and punishment, he is always set up for failure. Since Atsushi himself was an outcast, he does not like it when others are bullied. Nevertheless, Nakajima tries to overcome his fears and change his life. Thanks to his work at the agency and constant clashes with Akutagawa, he realized that he must leave his past behind, since it has absolutely no meaning in his current life. It is quite remarkable that, despite a terrible childhood and constant bullying, Atsushi was able to grow into a kind and compassionate person, for whom the life and well-being of other people comes first. Atsushi's ability gives him the ability to turn into a white tiger.