This is a history seminar where the lecturer, Dr. Hideki Tsuganesawa, the director of Tsuganesawa Dental Clinic, will teach about the roles and relationships of 'the strongest No. 2' using brothers who appear in Japanese history as a theme, under the topic 'Welcome to a Walk Through History.' Through the dynamics of leaders and their assistants, we will explore hints that can be useful in modern business and family relationships.