Ming Ming Li, also known by his hero alias Mian Long, is a fifteen-year-old boy who serves as the hero representing China in the world of Shy. In his civilian form, he has a short stature, messy black hair that reaches his back with a braid on the left side, and dark eyes. When he transforms into Mian Long, his hair becomes shorter, his eyes turn blue, and he gains two ahoge on his head. His hero costume consists of a white chiffon-style robe draped over a black bodysuit, white trousers, and kung fu shoes, along with Heart-Shift Bracelets on his wrists that synchronize his spirit into power, allow him to understand other languages, and enable communication with heroes from different countries.

Ming Ming has a habit of falling asleep at odd times and places, which reflects his power over sleep. He is self‑conscious about his androgynous appearance, which often leads others to mistake him for a girl, and he harbors a desire to become more traditionally manly and tough. This insecurity drives him to want to improve his combat skills. Despite his doubts, he is dedicated to his role as a hero and prioritizes rescue over direct confrontation.

His primary ability is inducing sleep in others. He can use techniques such as Ryumin Ken Tenshin-ryu 'Meisou', which creates long energy claws from his cuffs that cause intense drowsiness upon contact, and Ryumin Ken Hi-gi 'Shinshinshou', which emits energy from his right palm to immobilize a target. These abilities make him a valuable support hero who can neutralize threats without violence.

In the story, Ming Ming is a supporting character who interacts with the main hero, Shy, and other international heroes. He joins his comrades in major battles against the villainous organization Amarariruku, notably arriving with the team to confront the fused entity of Utsuro and Ai. His development centers on overcoming his lack of confidence and learning to accept his strengths while striving to become the hero he wants to be.