Visual Novel / Harukuru

Following

Harukuru. - Spring has come true? - (Harumade, Kururu. in Japan) is a Visual Novel written by Ryouichi Watanabe and released by Sumikko Soft in 2012. Sekai Project released an English translation in February 2025, altough it excludes the sexual content. HaruKuru paved the way for three other visual novels by Ryouchi with titles based on the other seasons: Natsukumo, Yururu, Akiyume, Kukuru and Fuyukara, Kururu.

Kazuki is spending the spring break in a remote, eerily quiet place with four girls named after seasons: Harumi, Shizuka, Akio and Fuyune. There's no internet connection and no traces of human civilization. The only buildings are an abandoned school in which they can only do computer tests and a luxurious dormitory with hot springs and a chimney that seems to stretch up to outer space. One day, Shizuka suggests to make a harem for Kazuki. Is this the start of his Romantic Comedy life or is there anything else going on...?

Beware that most trope names are spoilers, especially if you haven't finished reading the prologue.

Harumade, Kururu. contains examples of the following tropes:

• After the End: The story takes place around the year 10000, millenia after the Glacial Apocalypse killed most species and all human life on the surface. The only survivors are the main characters that are kept safe by the carnation system of the underground colony.
• Animal Motifs: Turritopsis dohrnii is a species of jellyfish with the unique ability to revert from an adult stage to an immature form, making it biologically immortal. It gives the name of the underground colony Turritopsis and everything inside it, including both objects and characters, has the same properties as the jellyfish. In each carnation loop, they age during 90 days and they de-age back again for another 90 days.
• Apocalyptic Underground Refuge: During the Glacial Apocalypse, humanity built several advanced underground colonies in to protect themselves from the extreme cold and advancing glaciers. The Turritopsis colony is the last one standing, thanks to its carnation system keeping the main characters alive and preventing its deterioration.
• Balanced Harem: In the prologue, the four girls spend equally enjoy screentime and moments with Kazuki and are perfectly fine with sharing him.
• Bedmate Reveal: Fuyune's arc starts with Kazuki waking up to find Fuyune sleeping next to him. He turns around and sees another Fuyune, who in reality is her clone Mafuyu. Both girls had planned to play a prank on Kazuki.
• Benevolent A.I.: The Automaton of Astrolabe is a management computer with free will that does everything it can to make the last remaining humans live prosperously. It convinces Shizuka to share some optimism with Kazuki and gives the group a chance for a future by moving Earth to another star.
• Cherry Blossoms: Earth warms up enough with the new star for the ice age to end and the characters are able to set foot on the surface. When they do, they are greeted by many blossoming cherry trees, representing that spring has finally come.
• Cruel and Unusual Death: Akio's arc kicks off with Fuyune's death. She is found lying down in her room with a swollen stomach because a large clock has somehow been inserted inside her, although no wounds are found.
• Disposable Decoy Doppelgänger: In Akio's route, after all the investigations on Fuyune's death, Kazuki and Akio find her alive and well. It turns out that Fuyune used her clone to engineer the murder case and test out Akio's intellect, while also giving hints that they live in a looping world.
• Dumb Blonde: Fuyune has blonde twintails and she is the least bright member of the group. She hates studying and makes jokes at inappropriate moments. Subverted with the reveal that she is the administrator and researcher of the underground world and that she has access to memories of previous loops.
• First-Episode Twist: In the 89th day when the long spring break is nearing its end, all five characters reflect on the fun they had as a harem and go to sleep together in the living room. However, no one comes to pick them up as they were promised in the instructions. Instead the time resets back to very first day of the holiday and everyone forgets what happened. Between those events, the POV shifts to an aquarium in which two unidentified people speak about the harem as if they were test subjects and about a system of "carnations".
• Genre Shift: The visual novel starts out as a harem nukige with lots of porn, but then it shifts into mistery as the characters explore their strange world and a murder case happens. In the penultimate arc, the story culminates its nosedive into hard science fiction, dealing with apocalypses, genetic engineering, AI and other such topics.
• Glacial Apocalypse: Around the year 3000, the Sun started decreasing the energy output to the Earth, causing a harsh Ice Age. Oceans dried up, wars broke out, resources and avaliable land got scarce. Even when humanity built Apocalyptic Underground Refuges, they went extinct save for the residents of the Turritopsis colony.
• Gratuitous English: Shizuka doesn't have the common sense that fish can be food. She is so terrified at Harumi cooking it that she screams "No!" and "Oh my God!" in English.
• "Groundhog Day" Loop: The 90-day-long spring break repeats over and over and in each reset, everyone forgets what happened in the previous loop as well as their identities. Later, it's revealed that the loop only affects the Turritopsis underground colony and that it's more like all matter and characters inside it de-age and age back again consecutively.
• Heroic BSoD: At the end of her arc, Fuyune passes the administrator role to Kazuki and he is getting weary from being aware of all the loops and the Glacial Apocalypse that will hardly be solved. One fateful day, he receives a message from a mysterious sender, the Automaton of Astrolabe, which tells that the Sun isn't regaining activity any time soon and thus the Ice Age will never end. Kazuki has all sense of hope shattered and kills himself. On the next loop, even if he lost his memories, he still feels immensely depressed and unable to do anything until Shizuka starts encouraging him.
• Human Subspecies: The Ice Age caused the acceleration of mutations in some humans, who became another species in the Homo genus. They have thick skin for protection from the cold at the cost of heavily decreased intelligence. When the time comes for Kazuki and Shizuka to propel the Earth towards another star, they face the dilemma of killing about 5000 of these hominids, but they decide to push the button and go through it in the end.
• I Call It "Vera": Shizuka is very fond of bossing the others around with her crowbar, and she calls it "Edoga-kun".
• Identity Amnesia: All five characters wake up in their dorm rooms without any recollection of what they did before. They don't even remember their own names and take on the season-themed names noted on pieces of paper. This amnesia repeats with each time loop.
• Infodump: While Fuyune guides Kazuki around the hidden corridors and the control room of the underground colony, she gives a very lenghty exposition about the situation on Earth's surface, the colony, and how they got there.
• In Medias Res: The story starts when 45 days have passed and Kazuki is somehow already in a relationship with the four girls at the same time.
• Manic Pixie Dream Girl: During her arc, Shizuka tries her darndest to cheer Kazuki up when he has fallen to utter despair, believing that there is no longer a future for Earth. She takes him to many activities like running, games and even pretends to be a magical girl of computers.
• Minimalist Cast: No other characters exist beyond the 5 main ones: Kazuki, Harumi, Shizuka, Akio and Fuyune. Later Mafuyu, Fuyune's alternate personality that materialized in the world, joins the cast.
• Orgasmically Delicious: Shizuka gasps and feels in heaven whenever she eats anything prepared by Harumi.
• Planet Spaceship: Near the end, Kazuki and Shizuka activate some rockets in Antarctica with the the help of the Automaton of Astrolabe. That way, they propel the planet Earth towards the nearest star so that it can warm up and end the Ice Age.
• Playful Cat Smile: The Automaton of Astrolabe appears as cat smile emojis on a screen, which fits its optimism and tendency to pranking people.
• Ripple-Effect-Proof Memory: As Fuyune has been appointed with the administrator role in the colony, she has her mind connected to a fourth-dimensional storage device so that she can remember all information from previous loops. When she Passes the Torch to Kazuki, he also has access to the memories of previous loops.
• R-Rated Opening: Less than 15 minutes in, Shizuka explicitly gets naked and a group sex scene comes up. A dozen more H-Scenes play out until the prologue is over.
• Running Gag: One morning, Akio's tongue slips as she says kon'nyan instead of konnichiwa. The other girls pick it up and make up a new salute, much to her chagrin. It repeats several times throughout the story like this:
  Person A: Kon'nyan!
  Person A: Un'nyan!
  Both: Nyan nyan!
• Self-Censored Release: The Steam version, available in English and Japanese, removes the risqué humor in addition to the usual practice of cutting the sex scenes. Some of that content can be restored through a patch that bumps the rating to 17+, but it still excludes explicit sex.
• Star Scraper: In the center of the dorm, there is an impossibly tall and thin tower that seems to stretch up as far as the eye can see. It's inaccesible and its purpose is unclear, though the characters think it's a chimney. The tower turns out to have the function of holding the ceiling of the artificial underground colony and containing the elevator to the outside world.
• The Stoic: According to the paper that contains his name, Kazuki is "broken" and has no expression. This means that his face is physically unable to show any emotion and that he has much less sensitivity to pain. Later explained by the fact that he was a result of an experment of genetically engineering males due to the rapid deterioration of the Y chromosome.
• Tamer and Chaster: The prologue is filled with a dozen sex scenes, but after it this content drastically decreases in favor of exploring what's going on with their enviroment and the developement of the individual harem members.
• Tears of Remorse: Akio breaks down in tears during her route because she feels guilty of seeing Fuyune's death as a puzzle to be solved and analyzed instead of showing mourning.
• Temporal Theme Naming: Each of the four girls' names contain a kanji for one of the four seasons: Harumi (春海) has "spring", Shizuka (静夏) has "summer", Akio (秋桜) has "fall" and Fuyune (冬音) has "winter". Kazuki (一季) contains the character for "season" itself.
• Tulpa: Between her neurodivergence and having to sit through many time loops while remembering everything, a second personality emerged inside Fuyune's mind. It has been growing crueler and arguing with Fuyune until eventually, it materializes as an independent Doppelgänger, now known as Mafuyu.
• Voluntary Vampire Victim: A non-supernatural variation. During Harumi's arc, she reveals that she has been resisting an urge to kill people for a long time. Kazuki enters an agreement in which he offers up to be stabbed little by little by Harumi because he feels much less pain than usual. Harumi interprets this action as killing him slowly, so it eases her bloodlust.
• When He Smiles: When the group finally gets to exit to the surface and sees the beautiful scenery with Cherry Blossoms, Kazuki is filled with happiness and smiles for the very first time. The girls are all emotionally moved by the smile.