Calisthenics
I took these pictures on a train station platform on Sunday, October 14, 2018.
It's a daily sight, but not universal, to see people doing calisthenics in public - on train station platforms, in parks, at bus stops, and elsewhere. I've seen old ladies swinging from the overhead hand straps on early morning (not very crowded) trains like monkeys in a zoo. They're just doing stretching exercises.
In addition to that, it's a common sight to see people, usually men, practicing their golf or baseball swings with imaginary clubs and bats and even their baseball pitches in public. What’s up with that? Japanese believe in form over content. The most important thing is to master the form of something, and things like talent and proficiency should follow naturally. (Spoiler alert: never trust what a Japanese describes as “natural.”) Western foreigners, by comparison, habitually emphasize content over form. Fighting sports like Aikido, Judo and Karate emphasize "kata," well-rehearsed moves and postures. The object of these martial arts is not to hurt people so much as to achieve a transcendental consciousness through control of one's own body.