Serena Jounouchi, a 14-year-old French-Japanese idol and comedian introduced in "Pretty Rhythm: Aurora Dream," resides in Kyoto with her French businessman father Steven and Japanese mother Karen from Kyoto. She balances school with her entertainment career. Physically, Serena possesses short blonde hair, sharp blue eyes, and fair skin. By "Dear My Future," her hair lengthens slightly, fanning outward with reshaped bangs forming an intake. Her fashion evolves, featuring a "Gold Devil One Piece" for performances with unit Serenon with K and a "Monotone Modern Coat" for casual autumn/winter wear in "Dear My Future."

Brash, hot-tempered, and prideful, Serena frequently mocks rivals she deems inferior, displaying fierce competitiveness—particularly toward former Prism Queen Mion Takamine. Her rivalry drives repeated challenges against MARs, including defeating Aira and Rizumu at the Summer Queen Cup, which she later boasts about. Despite her arrogance, she unconditionally supports her best friend and comedy partner Kanon Toudou. As the "boke" in their manzai duo Serenon, Serena leverages Kansai dialect for comedic timing. In "Dear My Future," she matures, advising younger idols like PURETTY and adopting a calmer demeanor.

Debuting in "Aurora Dream" Episode 20 with Kanon as MARs rivals, Serena ridicules Aira and Rizumu during a tournament. Their coordinated Prism Show outfits and victory force MARs to strategize anew. Serena competes against MARs in events like a basketball match organized by Yuri and an Okinawa survival contest to find the Venus dolphin, where her shark costume disguise fails. After her Prism Show agency dissolves in "Dear My Future," Kyoko Asechi recruits her and Kanon into Pretty Top. They continue manzai and unit activities as Serenon with K, now including Kaname Chris. During the P-nation event, Serena mentors PURETTY on Prism Star pressures and performs a Manzai Prism Act with Kanon and Kaname.

As a Prism Star specializing in "sexy"-type performances, Serena executes jumps like "Hattrick Serve," "Prism Rainbow Hurricane" (featuring tornado illusions), and "Smile Heart Dive Duet" (with heart-shaped motifs) alongside Kanon, blending comedy and dynamic visuals. Her name, meaning "clear, tranquil, serene" in Latin and Greek, contrasts her fiery nature. Her surname, meaning "within the castle," shares a connection with Yu-Gi-Oh!'s Katsuya Jonouchi, noted for similar blonde hair and personality. Serena is one of three arcade characters adapted from "Pretty Rhythm Miniskirt" into the anime.