They first appeared in the original Splatoon (2015) as a pop music duo known as the Squid Sisters (Japanese: シオカラーズ, Hepburn: Shiokarāzu, lit.

Artist Seita Inoue also wanted to capture the "homemade feel" of upcoming idol presentations on radio programs and late-night shows, illustrating them as characters whose popularity had not quite exploded.

The designs for them were originally conceived by one of the developers who created the generic non-playable characters for the title, with Inoue drawing their art afterward.

These "messages" would have actually been sound waves that traveled from present day conversations to another planet and back to Splatoon's version of Earth, which was set 12,000 years in the future.

[6] Several outfit designs were considered, with military or casual themes suggested, though the development team focused on differentiating them from the player models.

The pair had not met each other prior to their audition, and weren't aware the characters were a duo, only knowing at the time it would be a Nintendo game.

To get a better feel for their roles, keity.pop wore makeup akin to "Western" musicians coupled with miniskirts and pink Dr. Martens boots.

[8][9] Despite the duo being referred to as the Squid Sisters, Callie and Marie are actually cousins,[10] and are the granddaughters of Cap’n Craig Cuttlefish, a veteran of a major conflict known as the Great Turf War.

[17] For the Grand Festival Splatfest, Callie and Marie collaborated together with Pearl and Marina, known as Off The Hook, and Shiver, Frye, and Big Man, known as Deep Cut, to form the supergroup Now Or Never Seven to perform a new song in honor of the celebration.

[22] In celebration of sales for Splatoon reaching one million units in less than a year, a live holographic concert of the Squid Sisters was announced by Nintendo in December 2015.

[24] More concerts were held worldwide, such as in Paris, France on July 12, 2016,[25] and they continued into 2022, eventually featuring Off the Hook and Deep Cut, the idols of Splatoon 2 and 3 respectively.

[30] During the final Splatfest, Nintendo released printable alternate cover art for Splatoon as a celebration and way for players to further show their support to their side.

[31] Callie and Marie have been subject to a large amount of praise from fans and critics, and the two have been considered the primary mascots of the Splatoon games.

Nadia Oxford of USGamer described the events of the series to be "tragically effective", and a "real heart-punch for anyone who's been part of a dissolving friendship or relationship".

[8] The influence the events had on Splatoon 2 were praised by Connor Sheridan of GamesRadar+, describing it as a "fresh idea" and a "pleasant surprise", while also saying "I don't know if my heart could stand a war between the Squid Sisters".

[41] Other publications, such as Kotaku, wrote that the Squid Sisters made great virtual idols,[42] and they are recognized as pop icons by Polygon.