"Nobles and maids cannot be together. Crossing that line will only bring you misfortune, Master."
— Minato Aqua
AQUARIUM is a Romance Visual Novel spin-off of hololive, featuring Minato Aqua (who is also the producer), Shirakami Fubuki and Houshou Marine. It was developed by Entergram and released only in Japanese for PlayStation 4 and Nintendo Switch on October 27, 2022. The English version and the Steam release were announced on December 30, 2022 and were released on October 26, 2023.
Theo, the young lord of the François mansion, has been having the same "nightmare" for a decade. His family hire a new maid for him, so he can grow up healthy and inherit the mansion. However, despite being a noble, he gets interested in a forbidden love with this newcomer, who he may have met when they were kids.
"Stay Blue" is used as the novel's opening and "Cassiopeia" as the ending theme. The novel includes 3 chapters plus an unlockable extra chapter that occurs before the 3rd but is otherwise disconnected.
AQUARIUM provides examples of:
- Amnesiac Hero: Theo at some point in the past had a heavy fever that made him lose all memories of his childhood. Despite having regular dreams, he forgets everything other than "some girl yelled at him", so he can't piece together that Aqua is her. She also isn't allowed to talk about it as doctors say he needs to remember everything by himself.
- Anachronism Stew: For a standard late medieval setting, Aqua's casual clothes and swimsuit are quite modern.
- Arc Words: "Broken bonds can always be mended." is mentioned several times in reference to Aqua and Theo's complicated relationship.
- As Himself: Aqua, Fubuki and Marine play themselves in a medieval setting. The modern Aqua Minato's livestream is used at the end of the novel in a Or Was It a Dream? segment. Notably, Fubuki being a token fox girl isn't questioned and a sprite of Theo shows this isn't shared among the Francois family. She also keeps surname Shirakami in the story. The dialogues still imply they are siblings.
- Beach Episode: In Chapter 3 Theo and Aqua go to the beach and Aqua tries her first swimsuit.
- Big First Choice: The first choice in the game asks Theo if he wants to push on with his joke advances on Marine even if they both will get kicked out. The game asks three times if you want to "set sail" with Marine before an implied offscreen sex later the game sets onto a comedic Marine route. With the route being rather short and generally nonsensical, it's a clear Non-Standard Game Over.
- Big Sister Instinct: Since their mother's passing, Fubuki doubles as Theo's protective mother figure.
- Birthday Episode: Aqua's birthday falls on August 8thnote , which happens to clash with an noble tea party. When Theo wants to make Aqua a present, Fubuki tells him that it can't be that important, and Aqua lets them go. Theo is so unsatisfied he makes her a Love Confession at night.
- Bookcase Passage: Of the mansion's cupboards is blocking the passage to the outside.
- Breaking the Fourth Wall: In "Marine's Route", Aqua barges in (despite not being introduced yetnote ) and says that the game is titled AQUArium, so Marine shouldn't even be a romance option, before the two fight over the protagonist role and Marine hijacks the plot, with the ending being non-canon.
- Cannot Spit It Out: Aqua can't tell Theo she's the girl from his dreams because it may negatively affect his amnesia recovery. And also because they can't be romantically involved. Theo also falls in love with Aqua, but similarly can't say it due to his higher social status.
- Canon Foreigner: The Francois family are not based on any of the Hololive content.
- Cerebus Syndrome: After the rebellion was continuously alluded to, Evil Uncle's forces suddenly attack the mansion in Chapter 3 in an otherwise Slice of Life story with no intent of leaving anyone alive. A cat dies and so do the protagonists.
- Charm Person: Marine can apparently shoot "Sexy Beam" from her finger, which she uses to hypnotize Fubuki into approving her relationship with Theo and a few townsfolk to "sell" a ship to her. With it ending on a Non-Standard Game Over, it's not canon.
- Chekhov's Gun: While the reason is different, Theo and Aqua end up trapped at the end of a cliff similarly to the noble and the maid in the book narrated at the start of the novel. They don't end well either.
- Childhood Friend Romance: Theo has met Aqua on a beach 10 years ago, and she returns as his potential love interest.
- Children Are Innocent: Younger Minato not only doesn't know what social status is, she thinks Succession Crisis in the Francois family could have been resolved by simply talking it out and doesn't know anything about marriage aside "being together forever".
- Company Cameo: The Francois family crest has a Hololive logo in the middle.
- Didn't Think This Through: Fubuki specifically hired Aqua because Theo talked about a girl in his nightmares, and she wasn't hard to find. She thought this would finally make him feel better, but didn't consider much they may view each other romantically, which isn't allowed.
- Diegetic Soundtrack Usage: Aqua sings her own theme, "Aqua Iro Palette", at the chapel.
- Double Entendre: When Marine catches Aqua sleeping in Theo's bed, she assumes the two have "landed port". She also have a different idea about "setting sail" with someone.
- Epunymous Title: AQUARIUM is based on Aqua Minato's name.
- Everyone Can See It: After the Love Confession, Theo and Aqua try to keep their relationship a secret. In Chapter 2 Marine can tell at a glance that Aqua has a different attitude when talking to Theo, and under pressure makes her spill out what's happening between the two, and Fubuki figures it out shortly as well because they look like they're flirting.
- Fake Aristocrat: Aqua tries to go to town in rich clothes, but gets overwhelmed by high prices and high heels eventually make her feet hurt. This gets noticed by a kid and Aqua fails to persuade him with a Noblewoman's Laugh.
- Festival Episode: The extra chapter is Theo and Aqua coming to Villance to watch fireworks and do other local activities until then.
- Fitness Nut: Theo regularly exercises to become a strong person, as he believes that's what his father expects of him. Aqua finds his muscles fascinating.
- Forbidden Love: In this setting nobles and peasants not only can't romance, even treating Aqua as more than a servant can get Theo banished, which everyone reminds him repeatedly. After them becoming Official Couple, this doesn't get much explored, as Fubuki helps them out.
- Forgotten First Meeting: By the present, Theo has forgotten he's met Aqua when they were kids, and she's can't bring it up due to her status and promise to Fubuki.
- Foreshadowing: In case it wasn't clear who the second main character is, near the beginning, while discussing Theo's dream, Fubuki says that he'll hopefully meet that girl soon, winks, then apologizes for winking. She also asks if "Aqua" sounds familiar, way before she explains her reasoning for hiring her is to help with Theo's amnesia. This is shortly before the familiar maid's debut.
- The Gambling Addict: Trying to impress Theo with the ring tossing game in the bonus chapter, Aqua goes through effectively five stages of grief before she finally got one in.
- Gilded Cage: As a noble heir, Theo has effectively even less freedom than a maid Aqua as he can't do anything that would hurt his prestige, while Fubuki takes care of everything until he can take care of himself. He gets to explore the local town in the story while not knowing much about it.
- Height Angst: Aqua has some annoying difficulties cleaning because she's not as tall as Marine. She borrows a stool later.
- Heir Club for Men: Fubuki can't be given a mansion because she's a woman. She has more authority, but only until Theo takes position.
- He-Man Woman Hater: A few shipbuilders have tripled the prices after Marine started negotiating, simply because a woman shouldn't be buying one.
- Heroic Sacrifice: The stray cat Aqua found later helps her and Theo escape the burning forest and warns them about debris before being fatally hit. They still fail to get out.
- Honor Before Reason:
- On Marine Route, even though Theo could get them a boat if he'd say his name, Marine tries to do it on her own and fails because she's seen as a weak woman and also still wears a maid outfit, then she resorts to hypnotism because she really wants it to be "her ship".
- Aqua wants to do all of her maid duties by herself without help, despite not being very competent or physically strong.
- Hotter and Sexier: Compared to other Hololive's media, the game's marketing puts a lot of focus on light Fanservice of the three girls, which proved to be accurate, and the writing has a few adult jokes.
- Inconsistent Spelling: The dialogue boxes use "Theo" while the transition screen shows "Teo".
- Instantly Proven Wrong: When Aqua accidentally drops a water bucket on herself, she praises her immune system from farmer days. Then immediately sneezes.
- Interclass Friendship: As a son of an aristocrat, young Theo wasn't supposed to hang out with young Minato, who was a farmer girl, but they did anyway for a while. Minato doesn't even know what "noble" means.
- Internal Reveal: Theo has no clue that the girl Minato and the maid Aqua are the same person, despite them looking identical, until Aqua take him to the same beach at the end of chapter 2. Since he doesn't recognize her until then, it's implied the dream shown is much more detailed than what he actually remembers.
- It's All My Fault: Aqua feels indebted to Theo for yelling at him as a child and causing him nightmares.
- Lap Pillow: Theo ends up asleep on Aqua's thighs after the work at Villance.
- Love Confession: At the end of Chapter 1 Theo confesses to Aqua despite the dangers of Forbidden Love and still not knowing they've already met, and they decide to keep it a secret.
- Meido: Just like her official vtuber backstory, Aqua gets to be a maid in training in a rich mansion. Marine works as Theo's senior maid.
- Multiple Endings: Early dialogue options can set the player on Marine's and Fubuki's routes respectively that are much shorter than the intended Aqua's. Notably these are the only times the novel has choices.
- Mythology Gag:
- When Marine tells Fubuki "kitty, come here", the first thing Fubuki says is that she's a fox and not a cat.
- In the game Marine can get her pirate ship like she's always wanted.
- When Theo catches Aqua, he remarks she must be about 44.5 kg.
- Fubuki failing to find a Golden Magipepper for days and disappointingly getting red ones is a reference to her Pokemon streams where she hunted the shiny Magikarp for almost 120 hours. It's also referenced in Chapter 3 when Theo says his sister spent a month trying to catch a shiny fish and only found red ones.
- Noblewoman's Laugh: While investigating a rumor, Aqua poses as a noblewoman, and whenever someone question's her identity, makes a loud laugh, which convinces nobody.
- Non-Idle Rich: Theo is sent to investigate the anti-noble rumors at the local town and ends up resolving them by having Aqua with her and giving people what they need.
- Or Was It a Dream?: The whole plot turns out to be a dream of an anime fan. Yet he feels suddenly saddened seeing Aqua Minato's livestream for the first time, she talks about having the same dream and she reacts to his comment.
- Overly Polite Pals: The orphanage's Sister tries to reward Aqua for bringing Sasha back and she refuses. This back and forth goes on for a while.
- Perverted Sniffing: Aqua takes her time to immodestly sniff Theo's pajama up to a Nosebleed. Theo happens to see the entire scene behind the door before a squeak revealed him.
- Pinky Swear: Young Minato and Theo made a pinky promise to meet again at the beach, which they did many times.
- Running Gag: Marine repeatedly says that Aqua is so cute she wish she gave birth to her, and eventually addresses her as her daughter to her annoyance.
- Saying Sound Effects Out Loud: Aqua spells out each of her "stare...".
- Secret-Keeper: Fubuki reluctantly decides she'll take responsibility if something happens if someone else clues in on Theo's and Aqua's romance.
- Sheltered Aristocrat: When Aqua gets them fried meat in a tissue in the bonus chapter, Theo is shocked that it's something commoners hold in hand instead of using dishes, fearing someone may view him as an animal.
- Shipper on Deck: Fubuki actually supports Theo's and Aqua's relationship, but can't let them be close due to public stigma. Figuring they became a couple anyway, she decides to prepare their potential marriage.
- Shrinking Violet: Aqua feels incredibly shy on her first day as a maid and sweats bullets during her introduction. During training before that, she's described as hardly speaking at all. She's always worried she does something wrong and refuses Fubuki's request to address her casually.
- Skirts and Ladders: Aqua cleans above the bookshelves, and, realizing that Theo is below her, panics, trips and gets caught by him.
- Star-Crossed Lovers: Nobles and peasants cannot be romantically involved due to current ideals of nobility, much to Aqua's pain. Theo practically can't even be nice to her because servants should be treated as such.
- Spotlight-Stealing Title: "Minato Aqua from Hololive" is prominently featured in the game's logo, despite having two other Hololive members as prominent characters.
- Succession Crisis: Theo's grandfather was the lord of the land. With his abrupt demise, his two sons had a rivalry until Theo's uncle got banished. Theo's father is still busy suppressing the coup at the story's time, and rebels eventually attack the mansion.
- Suicide Pact: The book Theo was reading features a noble Treize and his maid Emilie jumping off the cliff together when pursued after their love was discovered.
- Switching P.O.V.: The visual novel has a specific transition to indicate which character is POV even if they're on screen.
- Taxidermy Is Creepy: When Theo says that his father's room is decorated with hunting trophies, Aqua comments that she doesn't ever want to go there.
- The Tease: Marine's sexual jokes are well known in the mansion. Thinking that Theo is still asleep, she climbs on him and waits for him to wake up. When Theo tries to follow along as a joke as well, Marine panics that it'd be inappropriate for a nobleman.
- Unaffected by Spice: Fubuki covers her steak with so much "Devil's Sauce", Theo across the table has difficulties breathing, and she even gives him some and thinks his pain is him being overdramatic. After tasting her soup, Aqua and Marine pass out immediatelly.
- Uptown Girl: The main premise is romance between a noble Theo and a maid Aqua, even if it's considered dishonorable.
- "Well Done, Son" Guy: Theo studies a lot of imperial books and exercises to win his father's approval.
