Atsushi Nakajima is a fictional character in the manga series Bungo Stray Dogs, written by Kafka Asagiri and illustrated by Sango Harukawa. Atsushi also appears in the light novels based on the series and the 2018 film Bungo Stray Dogs: Dead Apple. He is an 18-year-old orphan who was thrown out of an orphanage—an experience that motivates him to find a reason to live. Upon meeting detective Osamu Dazai, Atsushi learns he has a supernatural power called "Beast Beneath the Moonlight" that allows him to turn into a large white tiger with incredible strength, speed, durability, and regenerative capabilities. Despite his lack of confidence, Atsushi has a pure heart and is protective of others, hoping to become a strong person by helping the weak.

Bungo Stray Dogs is a Japanese manga series written by Kafka Asagiri and illustrated by Sango Harukawa, which has been serialized in Kadokawa Shoten's seinen manga magazine Young Ace since 2012. Each character is named after influential authors throughout history, and their powers are based on said author's books. The series follows the members of the "Armed Detective Agency" as they try to protect Yokohama from the Port Mafia. The show mainly focuses on the weretiger Atsushi Nakajima, who joins others gifted with supernatural powers to accomplish different tasks including running a business, solving mysteries and carrying out missions assigned by the agency.