The show's cast consists of eleven characters: six main characters and five supporting characters.
- Seto, group leader/center
- Tsuyu, group mom and concert manager
- Nina, lead vocals, outfit designer and social media promoter
- Rei, lead dancer and assistant designer
- Bellerose, French appeal and karaoke café group promoter
- Robertoni, European representative and lead visual
- Kayo, practice coach
- Yurika, Student Council President
- Marko, clingy "ex-boyfriend" #1
- Platonic, clingy "ex-boyfriend" #2
- Yuzu, leader of MOMO★HOSHI, a fellow idol group aiming for the top
- My Friends...And Zoidberg: Seto is the odd one out in the group, to the point where he doesn't get along with absolutely anyone.
- Love Triangle: There are two in the series. One is between Tsuyu, Nina and Marco and the other is between Seto, Bellerose and Kayo
- Talking to Herself: Most characters are voiced by the same person, most notably five out of the six members in Gay μ's.
Seto Midori / 緑せと
- "DO YOU WANNA JOIN OUR AMAZING FANTASTIC AWESOME IDOL GROUP??"
A second-year and the founder of Gay μ's, Seto is an androgynous high-schooler (assumed to be a boy due to his short hair and overly-exagerated falsetto voice) who is really into idols and anime in general. Which is a nice way to say he's a weeb. He has an unhealthy obsession with Bellerose, whom he calls Rekardo-senpai (even though he's only one month older than him).
He is part of the sub-units RAINBOW PARADE, MIL Ky way and Love Triangle.
- Adorkable: At least he tries to be.
- All Love Is Unrequited: His crush on Bellerose.
- Attention Whore: He will do anything for attention. That's the whole reason he started the idol group.
- Berserk Button: Don't say his idol club will be a failure.
- Butt-Monkey: Everyone hates him. Everyone.
- Catchphrase: "DO YOU WANNA JOIN OUR AMAZING FANTASTIC AWESOME IDOL GROUP??"
- Crossdressing Voices/Larynx Dissonance: Although he is voiced by a girl, he still has a falsetto voice.
- The Ditz: The first thing he does in the show is trip and fall. Even the teaser trailer is just him falling.
- The Dreaded: He is so annoying that literally everyone just wants to get away from him.
- Dude Looks Like a Lady/Lady Looks Like a Dude: No one is sure if Seto is a boy or a girl, but he either looks like a very girlish boy or a very boyish girl.
- The Friend Nobody Likes: This assuming he even has friends.
- Hair Decorations: A green bow on the side of his head, mimicking Kotori Minami.
- Older Than They Look: He doesn't look 16 at all.
- Otaku: Weeb.
- Verbal Tic: As per usual by weeaboos, mixing random Japanese into his sentences.
- Too Dumb to Live: He seems completely oblivious to the fact that Tsuyu and Robertoni don't care about him.
Tsuyu Murasaki / 紫梅雨
- "WHY THE FUCK DOES HE GET THE PIZZA, I'M CALLING BULLSHIT!"
A second-year and the first member to join Gay μ's, Tsuyu is the self-proclaimed group mom and the one who arranges the concerts. She is also a kleptomaniac and will most likely steal all your prized possessions.
She is part of the sub-units after nine, Cringem@sters and 2x3.
- The Ace: Cutest in the group, gentle attitude towards others, good student and the most popular girl in school.
- Adorkable: The cutest girl out of all five and the face of the group.
- Animal Motifs: Her initial idol alias was Sushi (the creators later dropped the idea) and she is almost always seen with fish-related objects, be it keychains, necklaces, blacelets, etc.
- Beware the Nice Ones: She may look cute but can and will fuck you up.
- Big Eater: She seems rather furious at the implication of Robertoni getting more pizza than her.
- Deadpan Snarker: Not nearly as much as Nina and Robertoni, but still there.
- Kid with the Leash: As the group mom, she keeps everyone in control.
- Only Sane Woman: The most normal person in the group.
- Red Oni, Blue Oni: Blue to Robertoni's Red Oni.
- Schoolgirl Lesbian: Her first appearance in the series constitutes of her arguing with Robertoni over which is better, pussy or dick. She strongly defends pussy.
- Tareme Eyes: To the point where it looks like she's permanently wearing eyeliner.
- Team Mom: Self-proclaimed, even.
- Zettai Ryouiki: Wears black thigh-high stockings with her school uniform.
Nina Daidaiiro / 橙色にな
- "Listen up you little shit, youre gonna be an idol and you're gonna fucking love it or else your meme page is gonna be drop kicked into the Shadow Realm"
A first-year and the third member to join Gay μ's, Nina is a walking wave of negativity and the purest form of sarcasm. She is responsible for costume designs and the group's social media promotion, as well as knocking Seto unconscious whenever he gets too obnoxious.
She is part of the sub-units after nine, MIL Ky way and 2x3.
- Adaptational Modesty: An early concept art of the MIL Ky way sub-unit depicted her with an enormous bust, however it was heavily toned down in her animated design, where she is a B cup.
- Although this was a mistake due to being traced over a lily white CD cover, in which the artist (which has since left the project) didn't reduce her chest size to be on-model.
- Beauty Mark: Under her left eye.
- Girlish Pigtails: Almost always wears two low braids.
- Tareme Eyes: Out of all the characters, she has the most tareme eyes.
- Tomboy and Girly Girl: Girly girl to Rei's tomboy.
- Zettai Ryouiki: Wears lacy black thigh-high stockings with her school uniform.
Rei Akairo / 赤色零
- "WHO ELSE HAS A FUCKING TWENTY ONE PILOTS PHONE CASE YOU BITCH?!"
A first-year and the fourth member to join Gay μ's, Rei is a self-proclaimed hikikomori and an active Tumblr blogger. Although she might seem like a pretty explosive person, she is actually pretty shy and takes time gaining confidence on stage.
She is part of the sub-units after nine, MIL Ky way and Love Triangle.
Rekardo Jean-Pierre Bellerose / レカルドベレロース
- "Look, Seto, if you couldn't already tell by looking at me, I'm extremely straight. And a straight Frenchman does not partake in such nonsense."
A second-year and the fifth member to join Gay μ's, Bellerose is a French crossdresser who transferred to Otonokizaka due to his parents' work. Even though he is extremely effeminate, he claims to be completely straight, to everyone's disbelief.
He is part of the sub-units RAINBOW PARADE, Cringem@sters and Love Triangle.
- Fish out of Water: As a kid, his parents didn't teach him how to speak Japanese properly, so he called people random words he heard them say (e.g. calling Nina "Daidai" because her name is Daidaiiro).
Robertoni "Spaghettoni" Azzurro / ロベートニアズーロ
- "Seto I'm uninstalling Love Live from your fucking phone."
A second-year and the sixth and last member to join Gay μ's, Robertoni is an Italian ex-gang member who was forced to live in Japan to run away from the trouble he had in Italy. He rivals Nina in terms of sarcasm and hatred for Seto and has an obnoxious crush on Rei, his "farfalla rossa".
He is part of the sub-units RAINBOW PARADE, Cringem@sters and 2x3.
- Ambiguously Bi: When arguing with Tsuyu over which is better, pussy or dick, he defends dick but says he "gets where she's coming from" when she defends pussy, which indicates he might swing both ways.
- Deadpan Snarker: He is absolutely done with everyone's bullshit and won't hesitate to tell it straight to their face. Especially Seto.
- Embarrassing Tattoo: He has a tramp stamp which reads La piccola ragazza di papà, which is Italian for "Daddy's little girl". Yup.
- Red Oni, Blue Oni: Red to Tsuyu's Blue Oni.
Yurika Kuro / 黒ユリカ
- "DO YOU GUYS WANT ANYTHING OR DID YOU JUST COME HERE TO WASTE MY TIME?"
An extremely young-looking third-year, Yurika Kuro is the Student Council President of Otonokizaka Academy. She is ridiculously strict and wants to stop Gay μ's from succeeding for no apparent reason. She eventually teams up with Marko, since they have the same objective of spying on the group.
Marko "Cringe" съеживаться / マルコクリンジュ
- "TSUYU COME BACK TO ME!"
A 16-year-old Russian immigrant, Marko is Tsuyu's clingy ex-boyfriend, who sneaks into Otonokizaka to spy on her. His catchphrase, "Tsuyu come back to me", is said almost everytime he's onscreen. He eventually teams up with Yurika as means to spy on Tsuyu better.
Kayo Mizuiro / 水色加代
- "Hold on, let me just pretend I give a fuck."
A third-year, Kayo is a sports-addicted girl who takes an interest in the group when she sees how terribly coordinated their dance moves are. She later becomes their official coach.
- Tsurime Eyes: Complete with a kuudere personality.
- "My love for Rei is deeper than the cuts in my wrists"
A first-year who, much like Marko, breaks into Otonokizaka to spy on the idol group. Nobody knows his real name, but he goes by "Platonic_xxX", or just Platonic. He hung out with Rei during her emo phase, until she proclaimed that they were just platonic when their peers asked if they were dating. He then devoted his life to following Rei until she accepts his feelings.
- Younger Than They Look: Be it the eyeliner, the piercings or the unnecessarily edgy outfit, he definitely doesn't look like a 15-year-old.
Yuzu Aiiro / 藍色柚子
- "Nice to meet you, I'm Yuzu Aiiro. Welcome to idol hell!"
A second-year who is also aiming for fame and success as an idol with her idol unit, MOMO★HOSHI. She has a doll-like appearance and a charismatic smile however it turns out she's not nearly as nice as she seems, as she tries to sabotage after nine's performance.
Sudachi / すだち
A third-year who is part of MOMO★HOSHI and has a lot of female fans due to her boyish look. She is Yuzu's classmate and childhood friend and supports all of Yuzu's decisions She is also Robertoni's favorite idol.
Mikan / みかん
A highschool graduate who is part of MOMO★HOSHI and attracts a more mature audience due to her womanly figure and sweet voice. She is Yuzu's best friend and aids Yuzu in her plan to sabotage after nine.
Satori Midorikawa / 緑川さとり
Midori Kimura / 木村ミドリ
Yuzu Aiiro / 藍色柚子
Tomoe Kasshoku / 褐色トモエ
Mikan / みかん