Sanpou Shoujo

Aki, a thirteen-year-old girl with a natural gift for mathematics, discovers a mistake in a sangaku during a pilgrimage to Sensou-ji temple in Asakusa. Her sharp intellect quickly draws attention, and news of her talent reaches Arima Yoriyuki, the lord of the Kurume Domain, who is himself renowned for his work on the rational approximation of pi. He hires Aki to teach arithmetic to the region's princess.

However, Aki is not the only candidate for the position. She must compete against other geniuses and prodigies in a series of mathematical challenges. Her goal is not only to secure the job but to earn enough money to fulfill her dream of opening a school for poor children, where she can teach them arithmetic and give them a chance at a better future.