Rei Granger is a free-spirited, half-vampire child prodigy who debuted at age 10 as the visual standout, vocalist, guitarist, and songwriter for ST☆RISH. As the older sister of Luka Granger, she possesses the immense power of the Lycanthrope class. By age 19, Rei has grown into a world-class musician and performer. In her past, she balanced her music with a secret life as the superheroine "Dark Sparkle" (codename: Stormy), fighting alongside the Phantom Thieves of Hearts before retiring to pass her legacy down to the next generation. She's Ikuya Krishima's childhood friend, and later his girlfriend.

Akira Kirishima is the brave, trustworthy captain of the swim club and the older twin brother of Vida. His fiery personality is a massive crowd-pleaser that notably impacts his sister's friend, Noelle Shinomiya. Armed with great plans and ideas, Akira is dedicated to leading his team to victory and claiming the gold.

Kai Natsuki is a brilliant, tech-savvy strategist, swim club secretary, and teammate on Team Persona under Mirai. He is Vida Kirishima's boyfriend and Lio Fotia's friend/rival. Entrusted with the Snake Miraculous and its Kwami Sass, Kai transforms into the superhero Viperion, using the power of Intuition to help Vida on difficult missions.

Sass is the Snake Kwami of Intuition. Connected to the Ouroboros bracelet, he allows his current wielder, Kai Natsuki, to transform into the superhero Viperion.