Code 18

The "official" fourth game in the Infinity series, composed of Never 7, Ever 17, and Remember 11. However, unlike any of the previous Infinity games, this one has no involvement of either Takumi Nakazawa and Kotaro Uchikoshi, the series' main director and writers.

The story is focused on Hayato Hino, a student at Ryusei Academy, where he is a member of the school's Second Science Club. One day, Hayato attempts to test out his "Dragon Unit", a flight pack of sorts, by jumping off the roof of the school. At first, it seems to be going well, until he suddenly sees a girl falling out of the sky. He catches her, and lands to the ground. As soon as she wakes up, she slaps Hayato upon learning his name and runs off.

As the days go by as the clubs prepare for the school festival next month, Hayato receives a special chip from a science professor, Genkuro Kanbara, which, when put into his smartphone, might allow him to receive voice messages from the future thanks to it being made from a rare mineral known as the Agastia Stone. After installing the chip, Hayato finds that he is indeed receiving messages, but they're too garbled for him to hear properly. As he tries to figure out the nature of the messages, he has to deal with his own issues as the school festival gets closer and closer...

Despite following the idea of routes based around heroines, it is interesting to note that the game is linear, and contains very few choices.

This game provides examples of:

 * Adaptation Decay/ Adaptation Displacement: Both are discussed in Nanari's Route, who, when hearing of a movie adaptation of a book she read, mentions how the novel was apparently much darker than the movie. As for the latter trope, Hikari express surprise that there was a novel.
 * Alliterative Name: We have Hayato Hino, Hikari Haruna, and Tamaki Tatekawa.
 * Anguished Declaration of Love:
 * Big Brother Instinct: Yuzu's brother Shitora, though it's played with in that he's her younger brother.
 * Big Damn Heroes:
 * Big Eater: Takeshi, Hayato's fellow Science Club member, who enjoys eating all the time.
 * Bittersweet Ending:
 * Broken Pedestal:
 * Casanova Wannabe: Yoshito, who never really tries to make the moves on anyone, but is always making somewhat lewd comments.
 * Chekhov's Gun :
 * Cosplay Otaku Girl: Tamaki.
 * First Kiss:
 * First Name Basis: An important plot-point in Tamaki, Yuzu, and Nanari's routes, where all of them are initially unable to call Hayato by his first name (calling him either "Hino" or "Senpai"). A big shift in their relationship is noted when they finally can call him by his first name.
 * Headphones Equal Isolation: Arika wears a large pair of headphones around her neck.
 * Hey You: Arika never calls Hayato by his name, usually calling him either "you", or some variation of "stupid scientist". In her route, she eventually settles for calling him "Hayato Hino"
 * I Want My Beloved to Be Happy: In Tamaki's Route, Hikari helps Hayato out and encourages his relationship with Tamaki, even though she loves him.
 * Its All Junk:
 * Jet Pack: The Dragon Unit that Hayato's making is essentially this, but he's never made on that lasts very long, or has other problems.
 * Lost in Transmission: All of the voice messages Hayato receives are like this, which is why he can't understand most of them: he can hear part, but not all, of the message. Notably, how garbled each message is depends on the route: In Hikari's Route, he can hear more of it, can barely hear anything in Tamaki and Yuzu's Routes, can hear about half of it in Nanari's Route, and almost all of it in Arika's Route.
 * Luke I Am Your Father: is actually  daughter, though it's subverted that both of them know this and it's not supposed to be a secret: the only one this comes as a surprise to is Hayato, who was unaware. Her father's reaction is pretty much "Oh, guess I forgot to mention that."
 * Meaningful Name
 * Missing Mom: Nanari's mother has been dead for over ten years.
 * Mysterious Informant: The mysterious sender from the future who keeps sending Hayato voice mails.
 * Names to Know In Anime:
 * Ai Nonaka: Hikari Haruna.
 * Kei Shindou: Tamaki Tategawa.
 * Madoka Yonezawa: Arika Tokitou
 * Sanae Kobayashi: Yuzu Soraki.
 * Unsho Ishizuka: Genkuro Kanbara
 * Yasunori Masutani: Yoshito Asakura.
 * Yuko Goto: Nanari Torikura.
 * Official Couple:
 * Ouroboros: Mentioned by Professor Kanbara, who uses it as a metaphor
 * Parental Abandonment: Both of parents died in an accident a long time back.
 * Parental Neglect: Hayato mentions that both of his parents are overseas for work, and he has no idea when they'll get back. He doesn't seem to mind much, though.
 * School Festival: Most of the routes lead up to this, though exactly what Hayato does for the festival depends on the route.
 * Shipper On Deck: Not exactly a shipper, but in Tamaki and Yuzu's Routes, Arika helps Hayato realize that he has feelings for them, while in Nanari's Route, she tries to set Hikari up with him.
 * Shout Out: The Sky Tower looks very similar to Integral Tower from 12Riven.
 * Stepford Smiler:
 * : Averted:
 * Temporal Paradox:
 * Theme Tune Cameo: In her route, Hikari blatantly hums the game's opening song several times.
 * Trademark Favorite Food: Hayato and tomatoes, which extends to him drinking tomato juice as well.
 * Tsundere: Arika. Tamaki not only identifies her as one, but also calls her "Tsunderika" at one point.
 * Workaholic: Professor Kanbara is this, frequently staying in his office overnight. Hayato also has a few traits of this, as he sometimes neglects others in order to focus on working on machines.
 * Xanatos Gambit:
 * Yaoi Fangirl: Tamaki, who not only is a fan of yaoi, but apparently has written some yaoi doujinshi herself.
 * Shipper On Deck: Not exactly a shipper, but in Tamaki and Yuzu's Routes, Arika helps Hayato realize that he has feelings for them, while in Nanari's Route, she tries to set Hikari up with him.
 * Shout Out: The Sky Tower looks very similar to Integral Tower from 12Riven.
 * Stepford Smiler:
 * : Averted:
 * Temporal Paradox:
 * Theme Tune Cameo: In her route, Hikari blatantly hums the game's opening song several times.
 * Trademark Favorite Food: Hayato and tomatoes, which extends to him drinking tomato juice as well.
 * Tsundere: Arika. Tamaki not only identifies her as one, but also calls her "Tsunderika" at one point.
 * Workaholic: Professor Kanbara is this, frequently staying in his office overnight. Hayato also has a few traits of this, as he sometimes neglects others in order to focus on working on machines.
 * Xanatos Gambit:
 * Yaoi Fangirl: Tamaki, who not only is a fan of yaoi, but apparently has written some yaoi doujinshi herself.
 * Tsundere: Arika. Tamaki not only identifies her as one, but also calls her "Tsunderika" at one point.
 * Workaholic: Professor Kanbara is this, frequently staying in his office overnight. Hayato also has a few traits of this, as he sometimes neglects others in order to focus on working on machines.
 * Xanatos Gambit:
 * Yaoi Fangirl: Tamaki, who not only is a fan of yaoi, but apparently has written some yaoi doujinshi herself.
 * Yaoi Fangirl: Tamaki, who not only is a fan of yaoi, but apparently has written some yaoi doujinshi herself.