Rami Nanahikari, a naughty girl in her prime, has been raised from a young age and brought up by her grandparents to be the next Guardian of the Key to the Secret Treasure, known as "Ark", and is really a descendant of aliens who came to Earth in ancient times.

Wearing her bunny girl costume, Rami rides into battle on her trusty dragon, Spot, as she encounters various enemies such as tanuki, dogs, cats, monkeys, the Seven Lucky Gods, the U.S. military forces, the Russian Army, and a serpentine dragon, until she arrives at the ship of Dr. Pon Eho, a tanuki billed as the most intelligent creature on Earth with an IQ of 1400, his appearance being appropriate for the thief that he is.

Keio Flying Squadron was made by a small team of developers; director Yasushi Endo, game designer Satoru Honda, programmer Teruhito Yamaki, and composer Tsukasa Tawada, with art and graphics by Hiroshi Ogawa and Hitoshi Kakumu, and character designs by Hiromasa Ota and Takeshi Honda.

Since Victor Entertainment was originally a music company before its merge with Nihon AVC,[9] they had been developing products that brought out the potential of CD-ROMs.

He chose a bunny girl as the protagonist of the game, naming her Rami Nanahikari, and reducing her breast size in order to fit his vision.

[13] Rami was also going to have a slightly mature look with longer hair and fishnet stockings (later changed to tights) for her bunny suit, but those ideas were dropped.

The voices were recorded at Magic Capsule in April 1993, provided by Miho Kanno, Akiko Hiramatsu, Jōji Yanami, Keiko Yamamoto and Yusaku Yara.

[23] Keio Flying Squadron was Kanno's first time voice acting, with her playing the role of Rami, applying for it out of curiosity.

[31][32] In the United Kingdom, a playable demo disc for Keio Flying Squadron containing the first stage was provided by the Sega Pro CD magazine in its December 1994 issue.

[34][35][36] In July 2020, Limited Run Games CEO Josh Fairhurst stated that he tried to get a rerelease of Keio Flying Squadron going, but JVC would not do it without official blessing from Sega.

However, due to the Sega CD's limited success and the game's scarce distribution, it did not reach a wide audience initially.

[43] GamePro gave it a score of 80%, stating, "Keio moves as smoothly as it sounds, so novice players and serious shooters alike will enjoy it.

[46] Retro Gamer included it among top ten Mega CD games, calling it "a perfectly acceptable substitute" of Konami's Parodius that features "similar style of horizontally scrolling wackiness and puts the Mega-CD hardware to good use to produce some excellent cut-scenes and a brilliant CD-quality soundtrack.