Itsuki is an 18-year-old student. One day, while walking down the street, he is surrounded by a band of criminals. Murashige Ryouta tries to save him but Itsuki is perfectly able to defend himself from the thugs, having practiced Aikidou most of his life. Ryouta is impressed with Itsuki's strength and follows him to the house of his family. Ryouta begins to have a great fascination for Aikido but even moreso for Itsuki.