Conceived by the Ministry of Health and Welfare to commemorate the International Year of the Child in 1979, the Children's Castle holds various activity rooms for children of all ages (though most are geared to elementary-age kids and younger). The third floor, designed for spontaneous and unstructured play, features a large climbing gym, building blocks, a playhouse, dolls, books, and a preteen corner with billiards, foosball, and other age-appropriate games; there's also an art room staffed with instructors to help children with projects suitable for their ages. On the fourth floor is a music room with instruments the kids are invited to play, as well as a video room with private cubicles where visitors can make selections from a library of English-language and Japanese videos, including Disney films. On the roof is an outdoor playground complete with a wading pool (summer only; ¥200 extra admission) and tricycles, while in the basement is the family pool open to the public weekends only (¥300 for adults, ¥200 for children). Various programs are offered throughout the week, including puppet shows, fairy tales, live music performances, and origami presentations.