Shinji belongs to the Eighth clan in *Darwin's Game*. He has short brown hair and wears the standard Eighth uniform: a white sleeveless shirt, a black vest displaying the number "8" on the back, and jeans.

His personality is marked by pronounced cowardice and apprehension. He openly questioned the clan's actions during a police confrontation and visibly trembled before their leader, Wang. Though initially hesitant to kill other players, Shinji later attempted murder to demonstrate his loyalty to Eighth.

Shinji participated in Eighth's coercive and violent operations. He was involved in the capture and torture of Shinozuka Youta, a non-player friend of Kaname Sudō, helping to pin Youta down. After Youta was forcibly enrolled in the game and activated his telekinetic Sigil, he used this power to hurl Shinji backward into a stack of boxes.

As a Darwin's Game player, Shinji possessed a Sigil, but its nature and effects remain unseen as he never used it in any documented incident. For combat, he relied on conventional weaponry issued by Eighth, carrying a firearm during clan operations.