Although it used to center on historical events, there have been attempts to deal with subject matter other than historical events, such as international events and managerial theories nowadays, as its aspect of promoting the audience's understanding with easier subjects has been reassessed.
題材は歴史的事件が中心だったが、題材をわかりやすく解説し観衆の理解を深めるという点が再評価され、現在では国際的事件や経営理論など、歴史以外の題材を取り上げる試みもなされている。