Wakana returned to her family home in Japan after a long flight back from a tennis tournament overseas. She had won, of course, and now wanted nothing more than to sit back, relax, and spend some time with her teenage younger brother Munetaka. Her parents were still out of town and Ritsuka, the oldest sister, was out tending to her duties as a lawyer. That just left Wakana alone with Munetaka and she couldn't be happier Yo, Munetaka! Your favorite tennis playing onee-san has returned!