This film narrates the story of Yasui Santetsu, a 17th-century go master who shifted his focus to astronomy and developed a new calendar for Japan. It is inspired by the life of Santetsu Yasui (born December 27, 1639, and died November 1, 1715), who was named the first official astronomer during the Edo Period and later crafted the Jokyo calendar upon the emperor’s request.