Sayaka Kotani balances her role as school nurse and Breakwater Club advisor with unpredictable quirks, oscillating between professionalism and whimsy. A penchant for sneaking drinks during meetings fuels her antics, from pilfering members’ snacks to issuing absurd demands. Though prone to drunkenly flirting with students or commandeering their hauls, latent talents surface unexpectedly—her lifeguard reflexes sharpen during swimming drills, while hunting trips reveal meticulous butchering rituals preceded by solemn prayers.

Students sidestep her antics yet grudgingly rely on her expertise, whether evading her seafood raids or tolerating her drain on club finances, as when she demands reimbursement for pricey lifesavers. Her split demeanor shifts visually: languid closed eyes mask sudden slit-eyed intensity when sober or serious, mirroring her dual identity as both disruptive slacker and precise instructor.

Teasing over her unmarried status, particularly from Yuki, underscores insecurities beneath her comedic façade. While lacking overt growth, her chaotic presence strains club patience—crashing clam feasts drunk or bartering for shrimp—yet inadvertently unites members through mutual exasperation. Consistency defines her as an erratic but sporadically capable figure, weaving mischief with moments of unexpected competence.