The vocalist of SYMPHONIA who loves singing more than anything else. She is the spiritual center of the band, drawing in her bright and unique bandmates. She once struggled with the overwhelming power of her own voice, spending a lonely period unable to sing as she wished. However, meeting Kanna showed her the joy of connecting with others through music, sparking her dream of forming a band with friends. To Kanade, singing is not merely self-expression. Her reason for singing is to have someone listen and leave something in their heart. She is deeply attached to her members and truly enjoys her current life standing on stage with them. As the band's popularity grows, the fact that she can deliver her songs to massive audiences she once couldn't even imagine is a source of great joy for her. However, SYMPHONIA does not act to reform Underworld society. What Kanade desires is simply to deliver their music. What that song makes one feel is entirely up to the listener.

A cheerful drummer who loves blonde hair with black streaks, sunglasses, and outfits covered in belts. She praises her own fashion as "super cool," though her reputation among those around her isn't quite as high. She has a social personality that hits it off with anyone immediately, speaking in a lighthearted tone like, "Our band is seriously the best!" On the other hand, she is the practical leader who keeps the strong-willed members together and is one of the few voices of reason in the band. Her true identity is a daughter of the Demon King's bloodline. She has a past of running away from home, hating the strict family traditions and the value system where power is everything. Because of this, she never speaks of her childhood or family. She possesses powerful lightning abilities reflecting her royal blood, but she dislikes this power as sparks can fly unconsciously when she gets excited. She has been Kanade's best friend since the time Kanade suffered from her vocal power, and she took up the drums while supporting her. To Kanna, the band is a place that symbolizes freedom and the companions she chose for herself, rather than a life decided by someone else.

A mermaid with light blue hair and eyes, and a tail covered in beautiful scales. She usually wears a shell-themed outfit with a rough jacket thrown over it, always drifting about with a sleepy, listless atmosphere. She is extremely laid-back with a disastrously loose sense of time, often failing to show up at the appointed hour. Consequently, in her solo activities, it was difficult to even make a schedule work before she could even show off her skills. She used to sing in the raging dark seas according to mermaid customs, luring sailors to their doom. It was Kanade who appeared before her then. After being challenged to a singing contest and losing, she formed a bond with her. Since she originally handled the harp, she joined SYMPHONIA as a guitarist rather than a vocalist. Her skills are the real deal, perfectly executing even intense shredding with a cool face. Her singing ability is also exceptionally high, to the point where her acoustic performances have fanatical supporters. In a meritocratic society centered on demons, she is an outlier due to her status as a mermaid, but she doesn't care about the evaluations of those around her. She doesn't flaunt her strength or appeal to others with her efforts to be recognized; she simply enjoys music at her own pace. That thick-skinned nature is her strength for surviving the harsh Underworld.

A dragon-kin demon with green hair, sharp yellow eyes, and sturdy scales covering her body. While she can be fickle and blunt at times, she is deeply compassionate at heart and never forgets a favor. As her words "I always pay back my debts!" suggest, a sense of duty is the very principle of her actions. She was saved by Kanade and the others when she collapsed in a harsh frontier of the Underworld. To repay that debt, she underwent intense self-training on the bass. Although she is unfamiliar with music theory or basic knowledge, she won the position of SYMPHONIA's bassist through her wild instincts and extraordinary guts. In live performances, she values "coolness" above all else, sometimes putting on reckless displays. In particular, the contrast with Ruwei, who plays with a cool face next to her, is one of the highlights of the stage. She is very polite to fans, and her sincere attitude toward everyone has earned her a reputation for "god-tier service." However, she doesn't feel she's doing anything special and tends to deny it out of embarrassment when praised. Despite having impressive horns, her secret worry is that she loses all strength in her legs if they are touched. The gap between her rough appearance and her delicate sense of duty is Lapt's great charm.

An antique-style girl-type robot with white hair and exquisite joints. She has a calm and ladylike personality and speaks in a unique, somewhat stilted manner. Her words coexist with a mechanical impression and a pure heart. She empathizes very easily and is moved by even small events, but being a robot, she cannot shed tears. She was picked up by Kanade and the others after being deactivated for a long time in the frontier of the Underworld and joined the band as the keyboardist, a position that had been vacant. Her true identity is a prototype combat robot once developed in the Underworld. she can fire powerful beams from her eyes and possesses superhuman strength, easily carrying heavy equipment like giant amplifiers despite her slender appearance. Her learning ability is also extremely high, allowing her to skillfully handle everything from mastering performance techniques to daily chores. However, having been created for combat, she now uses her abilities to support her companions rather than hurt them. Her presence, watching over the outrageous Kanade and free-spirited Ruwei with a smile and devotedly helping Kanna and Lapt with their work, is the very healing soul of the band. To Eik, SYMPHONIA is a precious place where she can find her own raison d'être, distinct from her purpose as a weapon.