It has become customary for Japanese teachers, especially junior high school teachers, to supervise their students’ extracurricular club activities. However, the duties associated with club activities are causing teachers in Japan to be busier than those in other countries and are becoming a time-consuming, mental burden for teachers. Club activities in Japan have been an integral part of the Japanese educational system and school culture for almost 150 years. As such, they have ensured that many of the nation’s citizens experience artistic, cultural, and sporting activities, serving as a hidden curriculum in schools. This chapter describes Japan’s particular situation regarding club activities and the drastic reforms undertaken in recent years. Furthermore, based on the discussion of club activities, the peculiarities of the duties faced by Japanese teachers and the public education system will be discussed.