Tamaki Chieno initially served as vice-president of Root Academy's student council under president Souji Jikukawa. She strictly enforced school rules with perfectionist zeal, demonstrating unwavering dedication to her duties and consistently following Souji's directives. After Souji's resignation, she won the student council presidential election and assumed the role. By the third season, she advanced to third-year student status.

Her appearance features short brown hair, brown eyes, and a signature yellow hair pin securing her bangs. She is typically seen in the standard Root Academy uniform.

During the conflict with the Orpheus Order, she became a target and pawn in their mind control scheme, which specifically targeted key school figures. Her involvement reached a critical point when Souji Jikukawa, similarly manipulated, dramatically reappeared to challenge Kaito Daimon.

Her name holds puzzle-themed significance; "Chieno" derives from "chie no wa," meaning "ring of wisdom" – a type of mechanical puzzle. "Tamaki" also serves as a synonym for "wa," reinforcing the puzzle connection.