Shut commands within Dys Dark, the organization ruled by the witch Dyspear. He is one of the Three Musketeers, formed alongside Close and Lock, each forged from Dyspear's soul. His appearance features distinct elf-like ears, curled pale blonde hair, and green eyes accentuated by blue makeup and sharp teeth. Shut favors elaborate attire: a white hat decorated with blue roses and a feather, a ruffled suit, blue fishnet stockings, and boots. A lock-shaped brooch adorns his neck, and he often carries a blue rose. Following his departure from Dys Dark, his outfit shifts to a bright blue suit with shorts, a ruffled shirt, and he accessorizes by wearing Lock as a scarf. In his beast form, he manifests as a large lynx with light yellow fur and piercing red eyes.

Driven by a narcissistic and pompous personality, Shut obsesses over beauty while dismissing dreams as worthless. He reacts poorly to defeat, exhibiting sore loser tendencies. Beneath this exterior lies deep-seated timidity and fear, particularly triggered by Lock's growing power or Dyspear's wrath. His speech habitually ends with "~nomi." Key relationships define him: he develops an intense, vain infatuation with Twilight, captivated by her beauty and growing jealous when she empowers Lock. After Twilight's purification into Towa, he remains conflicted, still admiring her beauty yet now seeing her as an enemy. His interactions with Close are marked by abuse and simmering resentment, while Lock initially annoys him but later invokes terror. A pivotal bond forms with Miss Shamour after she treats him kindly, offering makeup lessons and gifting him a scarf, an act that ultimately influences his defection from Dys Dark.

Shut's story unfolds through repeated failures against the Princess Pretty Cures. He traps victims' dreams to create Zetsuborgs using the phrase "Shut Your Dream!", often targeting individuals he deems foolish like a karate enthusiast, a tennis player, and an aspiring idol. Witnessing Twilight's purification into Towa horrifies him. Dyspear demotes him for his failures, compounding his humiliation when Lock mocks his lost affection for Twilight. A turning point occurs during an encounter with Miss Shamour; after defending others against him, she offers unexpected empathy and makeup assistance. This kindness leads him to question his allegiance. Facing Dyspear's ultimatum, he flees in terror. His despair later triggers a beast transformation, purified by the Cures. Though initially rejecting Cure Scarlet's offer of redemption, he clings to Miss Shamour's scarf.

Shut ultimately defects from Dys Dark after witnessing Close's resurrection and abuse of Lock, which recalls his own mistreatment. He intervenes to shield the Cures from Close's attack and pleads for Lock's purification. In the final battle, he and Lock assist by countering Dyspear's vines. Following victory, stripped of his powers, he remains in the human world. He is last seen awkwardly greeting civilians in a rose garden while wearing the gifted scarf. His abilities include creating Zetsuborgs, firing lasers from his rose, slashing with claw-like nails, and transforming into his beast form as a last resort.