callie is the outgoing and excitable cousin of marie, both being the granddaughters of craig cuttlefish. the two have been inseperable from a young age, and perform together as the squid sisters. the two performed together at a youth folk singing competition as children, and won an award for their performance. however, it took many years for them to rise to fame as the squid sisters, with each working various jobs in places like walleye warehouse and pihrana pit to make ends meet. she is notably optimistic and positive, as a contrast to marie, who usually quips sarcastically in stage commentary. her commentary also tends to stray from being about the stage itself, as she is often distracted by cute or striking things.

also of note, she always praises her team at the end of a splatfest regardless of whether or not her team won. many of her splatfest themes are energetic or uplifting, such as representing love in the love vs. money splatfest, boke (funnyman) in the boke (funnyman) vs. tsukkomi (straightman) splatfest, and go all out! in the go all out! vs. focus on healing splatfest. her team won 25 of the 43 splatfest events hosted in splatoon worldwide.

in splatoon, callie is one of the two hosts of inkopolis news, a program that announces the stage rotation as well as hosting splatfest events. during the events of splatoon's octo valley mode, she and marie first appear to announce that the great zapfish has disappeared. they later act as a mentor to the player, agent 3, as agents 1 and 2 of the squidbeak splatoon, taking over in captain cuttlefish's absence following his capture by octarian forces after the defeat of the octomaw. callie and marie's identities as agents 1 and 2 respectively are kept a secret from the player until the final boss, with the two wearing disguises in their dialog portraits throughout octo valley.

following the events of splatoon, the squid sisters see a massive rise in popularity, with callie and marie choosing to step down as the hosts of inkopolis news following an influx of solo work, being replaced by pearl and marina of off the hook. with the extra fame and work, callie and marie had fewer and fewer chances to spend time together, causing callie to feel lonely and despondent. following her not showing up for a planned trip back to calamari county with marie, as well as the second disappearance of the great zapfish, marie goes to inkopolis square to recruit a new agent to find callie and the great zapfish.

in splatoon 2's octo canyon mode, marie recruits agent 4 to find callie and the great zapfish. throughout the campaign, marie recieves strange radio messages, which are found to be from callie, who has joined dj octavio and the octarians after falling under the influence of dj octavio's 'hypnoshades'. during the final boss, marie shoots the hypnoshades off of callie using a splat charger, freeing callie from their influence and reuniting the squid sisters. following the release of version 3.0.0, callie can be found with marie in octo canyon at cuttlefish cabin after defeating the final boss, where she can provide statistical information regarding the player's multiplayer performance and give a daily 'lucky weapon horoscope'.

in splatoon 3's return of the mammalians, callie, alongside marie and the captain, previously known as agent 3, has been scouting a previously-undiscovered underground shelter used by humans prior to the age of the inklings called alterna. the player, as the new agent 3, first encounters the trio on future utopia island in alterna following a cave-in above ground. following the defeat of the 3 bosses found in alterna, the new squidbeak splatoon work together to build a machine to cut through the fuzzy ooze blocking their path to the alterna space center, where craig cuttlefish has been taken captive. when they reach him, they found that he has been completely dehydrated; however, a tear from the captain revives him, albeit still pretty dried out. following mr. grizz into space, callie, along with marie, deep cut, and dj octavio, sing the calamari inkantation to hype up agent 3 as they fight him.

if that was hard to follow it's fine, the plot of splatoon 3 is silly as hell.

outside of story mode, callie can be found in at the studio in inkopolis plaza, provided that you have the expansion pass DLC. she can also be called using an amiibo, either at the amiibo box in either hub area or in photo mode. during splatfests, she can be found performing on the truck in inkopolis plaza.