Kanetsugu Gasou, a boy born to an originally rich family that lost it's wealth, is a chubby guy who introduced himself to Adagaki Aki as her childhood friend Masamune. He shocks the Adagaki's household by showing them a marriage proposal certified by his father, an old friend of the Adagaki's head of family. Henceforth he shall have an arranged marriage Adagaki Aki.