Yu-no: A Girl Who Chants Love at the Bound of This World is a 1996 visual novel adventure game developed and published by ELF Corporation. It was originally released as an eroge for the NEC PC-98 Japanese home computer and later ported to the Sega Saturn and Microsoft Windows platforms without the sexual content. The story follows the protagonist travelling between parallel worlds to solve the mystery of his parents' disappearance. The game uses concepts from science fiction, physics, mathematics, philosophy, history and religion to construct its fictional universe. The "Auto Diverge Mapping System" (A.D.M.S.) that displays the branching parallel worlds and storylines as a tree helps the player navigate the game world.
Yu-no was written and produced by Hiroyuki Kanno, and its FM-synth music soundtrack was composed by Ryu Umemoto, Ryu Takami and Kazuhiro Kanae, who had previously worked on titles such as Eve Burst Error (1995). Yu-no was well-received and influential in Japan, where it revolutionized the visual novel industry and in turn had an impact on the manga and anime industries, inspiring numerous visual novel, manga and anime works.
In 2017, 5pb. (Later Mages) developed and published a remake of the game for the PlayStation Vita and PlayStation 4. Spike Chunsoft released this version for PlayStation 4, Microsoft Windows, and Nintendo Switch in 2019. The game has also been adapted into a four-part hentai original video animation, a manga and novels, and a TV anime series by Feel that aired from April to October 2019. The TV anime series is licensed by Funimation and Crunchyroll outside Japan.
Gameplay The PC-98 and Sega Saturn versions of the game are slightly different. Unless otherwise noted, the following information describes the PC-98 version.
Players travel between parallel worlds using a reflector device that uses stones to mark positions as returning locations so they can retrace their steps and enter an alternative universe. The game implements an original system called Automatic Diverge Mapping System (A.D.M.S.) that at any time in the game displays a screen showing the direction in which the player was heading along the branching plot lines.
A.D.M.S. When a branch in the storyline nears, an indicator on the game's reflector device blinks. When the player's choice advances the storyline, their routes are recorded in the "divergence map" and the device plays a sound. The player is tasked with collecting eight jewels that are the power source of the reflector device; the divergence map shows the locations of all jewels within the storylines even before the player has reached them. In this way, A.D.M.S. is used to search through the parallel worlds. The divergence map displays time from left to right and concurrent parallel worlds are shown vertically.
Another noteworthy feature is the "jewel save". The jewels that power the reflector device can be clicked to place a mark on the divergence map, which consumes the jewel. The divergence map can later be opened and players can return to the mark instantly, regaining the jewel. If a jewel save is made before a story branch point, players can explore one scenario then quickly return and explore an alternative. This feature is akin to saving or loading the game. Key items can be carried from one world to another through the jewel save.
After the epilogue, a new feature called "Start with Best Equipment" is added. This essentially returns all jewels placed on the ADMS back to the reflector device and sends the player back to the start of the branch, with all 19 items in their inventory. Their map progress is also saved.
Prologue and epilogue Sections at the beginning and end of the game have a more traditional visual-novel-style gameplay, in which players choose commands like "Look" or "Speak" from a menu. There are no branching paths in these sections and the Reflector Device cannot be used until they end.
Synopsis Prologue The game begins with a linear prologue which introduces the setting and characters, taking place during a couple of days. The player controls Takuya Arima, a student in the fictional Japanese city Sakaimachi. Takuya had a frictive relationship with his historian father Koudai Arima, who has been declared dead after months of disappearance. Takuya barely remembers his biological mother Keiko Arima who had died when he was very young, and he now lives with his stepmother Ayumi Arima. Ayumi is still grieving the loss of Koudai after only six months of marriage and is increasingly busy with work. Eriko Takeda is Takuya's new homeroom teacher and school nurse from abroad; she has become addicted to smoking and, unfamiliar with Japanese standards, took up Takuya's advice to dress skimpily. He meets Koudai's research partner and Sakaimachi Academy's headmaster Kouzou Ryuuzouji, who requests Koudai's belongings. His secretary is Mitsuki Ichijou, a former teacher and lover of Takuya. Some other students at Takuya's school include recent transfer student Kanna Hatano, the mayor's daughter Mio Shimazu, and Masakatsu Yuuki. Takuya meets Ayumi's underling Hideo Toyotomi, whom he takes an instant disliking to.
On a nearby beach, there is a tower-like rock formation going by the names Sword Cape and Triangle Mountain, at the foot of which stand two rocks dated as 8000 years old with unknown, 400 years old writing on them. Geo Technics, the company Ayumi works for, is occupying the beach as a construction survey site, but the workers are constantly injured by inexplicable lightning strikes. Kanna habitually warns people to stay away from the area.
One evening Takuya receives a package containing an incomplete letter from Koudai and a small otherworldly device with several slots, some fitted with round jewels. The letter talks about Koudai's theory of history and multiple timelines, tells that Koudai has departed elsewhere rather than having died, that the device (known as the Reflector Device) can be used to turn back time, and that Takuya should find the missing jewels and afterwards come to Sword Cape 10 PM that night to meet somebody. Takuya arrives (without all the jewels) and encounters there a naked blonde woman, who upon awakening kisses him, dies and vanishes from existence. Ryuuzouji and Ayumi arrive; Ryuuzouji demands at gunpoint Takuya to hand over the Reflector Device, but a sudden spacetime distortion shifts Takuya to an alternate timeline where he's alone at Sword Cape.
A.D.M.S. section At this point the Reflector Device becomes usable and the story starts to split, each main route focusing on a different female character. Jewels are found at various points throughout. A phenomenon known as Chaos Correction will loop Takuya to the beginning of this gameplay section after about two days of in-story time, that is, at the end of a route; his items but not memories are retained whenever crossing time.
After initial confusion, Takuya returns to sleep at home. The next day, he discovers that Ayumi is all right; however, neither she nor Ryuuzouji remember the confrontation from the night before. By this time Koudai's study, locked the night before, has been emptied and its contents delivered to Ryuuzouji.
In Ayumi's route, she faces stress and humiliation from the city populace demanding the work on the beach to be stopped. Toyotomi stages a thug attack on Ayumi to steal valuable Geo Technics documents and "saves" her to earn her gratitude. Takuya can't convince Ayumi that Toyotomi is merely manipulating her, until he receives from opportunistic reporter Kaori Asakura a photo proving the connection between Toyotomi and the thugs. With the Reflector Device he arrives home early enough to out Toyotomi before the latter causes Ayumi to commit suicide. She reveals that Geo Technics is actually mining at the beach for a mineral called the Hypersense Stone, which reacts to the human mind but changes its properties upon air contact unless preserved with a formula she was developing. In Mio's route, Mio and Takuya discuss a controversial theory by Koudai Arima positing that every 400 years a cultural shift occurs in Japan and that a race known as the Celestials is involved; Mio hypothesises that the Celestials and Sword Cape are connected. Yuuki spies Takuya and Mio together and, in a fit of jealousy, anonymously leaks sensitive information he overheard about Mio's father to make it look like Takuya betrayed Mio, which backfires as the ensuing scandal prompts her to plan emigrating soon. Now rushing to finish her research, Mio becomes trapped in a hidden cave system she discovers beneath Sword Cape, and Takuya goes rescue her. In the caves are found an underground lake filled with glowing raw Hypersense Stones; inside the hollow rock mountain itself a tall alien machine causing the lightning strikes, zapping the workers whenever they try to transport mined Hypersense Stones away; and a passage leading to a dry well behind Ryuuzouji's mansion. In Mitsuki's route, she confides to Takuya odd personality changes she's observed in Ryuuzouji, such as that he's become obsessed with something, has begun smoking, and that his mother Ume Ryuuzouji became suspicious of him but reverted. Ryuuzouji has recently moved into a mansion, on the lands of which an unidentified torso has been discovered, inspiring rumours about a curse. During Takuya's and Mitsuki's investigations, he comes across near the mansion a recently built shed that's become ramshackle overnight, and that Ryuuzouji got rid of his entire furniture and prefers to sleep on a bare floor. (In another route Takuya witnesses Eriko sleeping on the floor.) After Mitsuki becomes controlled by Ryuuzouji via Niarb (a type of hypnosis according to Eriko) and kills Ume, whose corpse holds Ryuuzouji's journal revealing his encounter with a "devil" woman and subsequent descent in ableness, Takuya teams up with Eriko instead. In the shed, behind a metal door is a secret passage to the mansion and a broken interdimensional vehicle, and hidden within the shed's walls are skeletal limbs and a skull. Eriko accuses Ryuuzouji of being an impostor who killed the original and removed the head and limbs to obfuscate his identity. After Mitsuki dies defending Takuya from an escaping Ryuuzouji, Eriko explains her death was scientifically fated. In Kanna's route, Takuya sees her being sickly and fainting, and is shocked to find her living alone in a bare apartment. Takuya finds there bank notes documenting Koudai giving Kanna regularly money until his disappearance, and an ancient photo; it depicts Kanna hugging a woman at Sword Cape with a visible third rock, which reportedly was destroyed 50 years earlier. Kanna wears a necklace with a stone, which she says she needs to live but that it'd be destroyed by water. A private investigator named Atsushi Houjou steals it to blackmail her for information about Koudai, resulting in a fight at the city park. Eriko arrives, incapacitates Houjou and explains he was controlled with Niarb, but the stone is dissolved in the park fountain and Kanna starts dying. She tells her life story, revealing that she was born long ago to the woman in her photo, who had arrived from another land; that she grew up to her current teenager appearance much faster than normal humans and stopped aging, like her mother and Keiko; that since her mother's death she lived as a prostitute; that she moved to a new location close to Sword Cape whenever her abnormalities were found out; and that Koudai and Keiko Arima adopted her for some time. Takuya saves Kanna with a stabilised Hypersense Stone stolen in another route from Geo Technics, after which she gives the key to Koudai's study.