Ruka Shirosugi

Ruka Shirosugi is a nurse who runs the first-aid station at the same beach as the Lemon Beach House. While Ruka appeared to be kind and caring on her debut appearance, treating Ika Musume and Sanae Nagatsuki who had passed out with heat stroke, she turns out to be the opposite in later appearances, showing her true colors as a strict authoritarian who refuses to treat repeat visitors to the first-aid. She also makes sure lifeguards Gorō Arashiyama and Tatsuo Isozaki uphold this rule of hers, because in her words, the security of a first-aid will let more people believe they can risk themselves while at sea. Goro and Tatsuo later find out that she only imposes this rule to relieve the burden on herself so that she can watch TV. Ika later discovers that Ruka has another hobby - drawing. Her drawings appear as deformed versions of what she sees, which she is embarrassed about. At one point Ruka summons Ika over for advice on how to improve her art. Ruka also cares for her former high school friends enough to try to convince them to leave their delinquent lifestyles like she and Mari did.