Atsushi Nakajima is a fictional character from the anime series Bungou Stray Dogs, not Shingeki no Kyojin. He is the main protagonist of the series and a member of the Armed Detective Agency. Atsushi possesses the ability called 'Beast Beneath the Moonlight,' which allows him to transform into a white tiger with immense strength and regenerative capabilities. Despite his troubled past and lack of self-confidence, Atsushi grows throughout the series, learning to understand his worth and becoming a pivotal figure in the agency's efforts to combat various threats and adversaries.