Siro Amai, also known as Syrup, is a fairy who first appears in *Yes! Pretty Cure 5 GoGo!* and works as a delivery boy. With the help of his partner, Mailpo, he can transport any letter to any destination. He possesses two alternate forms: a human form and a giant bird form used for aerial transportation.

Suffering from amnesia, Syrup cannot recall his past, which drives his central motivation to find the Rose Pact. He believes it will grant him access to the Cure Rose Garden and restore his memories. It is later revealed he was raised by Flora and was tasked with delivering a letter to Boss when Anacondy attacked him, causing his memory loss. After an unsuccessful attempt to remain in the Palmier Kingdom due to distrust of Coco, he joined the organization Eternal while still pursuing his dream of finding the garden.

Initially distrusting and hostile, especially toward Coco, Syrup gradually spends more time with the main group, often questioning his own reasons for doing so. Over time, he becomes more friendly and trusting. His personality is straightforward and hardworking, but he also greatly loves pancakes and often seeks opportunities to eat as much as possible, leading him to take a job at a school lunch cafe.

In his human form, he uses the alias Amai Shiroh—a pun where “Amai” means “sweet” or “sugary,” referencing Syrup, while “Shiroh” is written in katakana and pronounced like the Japanese word for “white.” In this form, he appears as a boy with scruffy hair, an orange uniform, a brown shirt, a red necktie, and a blue waist-bag. As an adult, his human form features more ruffled hair, a light brown vest, a beige long-sleeved shirt, dark green trousers, and brown shoes, still wearing the red necktie.

Syrup’s relationships shape his development. He initially acts harshly toward Urara Kasugano but gradually bonds with her, inspired by her kind and accepting nature to learn music. With Yumehara Nozomi, he first finds her strange but later befriends her, valuing her sympathy during his loneliness and nightmares. His relationships with Coco and Nuts are strained by grudges, though he eventually warms to them. He deeply cares for Flora, whom he sees as a mother figure, and is heartbroken by her death.

In a significant betrayal, influenced by his grudge against Coco and tempted by Anacondy, Syrup steals the Rose Pact to hand it to Eternal. However, upon remembering his positive experiences with the group, he refuses to betray them and is ultimately forgiven, solidifying his role as an ally.

In *Kibou no Chikara ~Otona Pretty Cure '23~*, Syrup is shown overseeing the Cure Rose Garden. There, he discovers a mysterious new flower bud that blossoms into Nozomi’s Time Flower. He assists by delivering letters to help Nozomi stay in touch with Coco. In one instance, he rescues characters from threats in his bird form and delivers a crucial letter. He later visits the adult Urara and reveals her music helped the garden’s roses bloom, admitting he began playing music because of her influence and agreeing to write a song for her. He also assists Cure Lemonade by transporting her inside phone networks to battle enemies.

Syrup ends his sentences with “~ropu!” and is the only mascot character capable of two transformations using his own powers.