Rin Shiretoko, nicknamed Rin-chan, holds the critical role of chief navigator and helmsman aboard the Harekaze, tasked with steering the vessel through perilous missions. Her precision under pressure clashes with a deeply ingrained instinct to flee conflict, a reflex honed since childhood through a "run-run existence" marked by abandoning situations or companions at the first sign of fear. Seeking solace, she often retreated to harbors to gaze at the sea, a habit that later fueled her resolve to join the Blue Mermaids and confront challenges rather than escape them. Raised in Shimane Prefecture near her family’s Hinomisaki Bay Marine Shrine, Rin developed an affinity for the ocean’s calming influence. This connection is tested when the Harekaze faces false mutiny accusations following an encounter with the Sarushima, triggering her urge to flee. Yet, acknowledging her irreplaceable role as helmsman, she begins transforming fear into calculated evasion tactics to protect her crew during pursuits. Prone to anxiety yet methodical in caution, Rin finds respite in marine biology and sketching dolphins, balancing her dislike of sandwiches with a preference for seafood pasta. Academically strong in biology and art but challenged by social studies, she anchors her leadership in unwavering loyalty to Captain Akeno Misaki, backing even the riskiest strategies with decisive support. Key growth emerges when she approves halting the Hiei’s assault on Chuuk Lagoon, rallying the crew by embracing Akeno’s bold plan. Though fear intermittently resurfaces, she steadily balances self-preservation with duty, inching closer to overcoming her "run-run life." Distinctive traits include opting for sneakers over regulation footwear and addressing Akeno with hybrid honorifics, blending respect with camaraderie.