Su An went to Japan with the expectation of part-time work and study, and found a part-time job opportunity in a public bathhouse called "Yunohana" in the old town of Tokyo. Bathhouse owner Shizu Sato is a gentle and tough single mother who single-handedly raises her daughter Aoi, a high school student, and Yuzu, a fifth-grade elementary school student. In the mist of the soup, Su An learned to take a bath and tidy up the bath utensils, and gradually developed a tender relationship with the Sato family that went beyond the employment relationship. However, a late letter home, a strange address unexpectedly sent by his father, and the occasional mysterious guest in the bathhouse made him unexpectedly reveal a secret that had been hidden for twenty years - that his seemingly ordinary father in China was actually the leader of the "Dragon Shadow Society", a gang organization spanning China and Japan. The fetters of blood, the pressure of survival in a foreign country, the undercurrent of the gang world, and the increasingly deep feelings with the Sato family push Su An to the crossroads of destiny.
