Koji is the rice fermented by aspergillus orizae, and is the foundation of Japanese foods, which include sake, shochu, sakekasu, miso, mirin, amazake, soy sauce and shio koji. All of the drinks and foods derived from koji have astonishing medicinal effects. The green tea and natto, which are not related to koji, have also equally great medicinal benefits contributing to the world longest longevity of Japanese. This book describes easy methods to make those foods and drinks, and how to use. This book also explains why and how those contribute to healthy life and longevity. In the present revision, three addendums are added: Addendum 1, the newest and simplest method of making koji using microwave; Addendum 2, how to make the sweetest amazake; Addendum 3, how to make soy sauce. This book was updated in March 2022.