This post was a reader’s request. Here’s to you, Megatron. I’ve been involved with sports in public school and in the community. I’ll generalize what I’ve seen.
The most popular sports are baseball and soccer. Baseball is often shown on TV. However, a lot of people get more into baseball during the playoffs. A lot of folks cheer for the local team at sports bars and pubs. People suddenly seem friendly and more open towards each other.
Soccer is more popular to play than it is to watch, especially with younger students. I haven’t heard of any girls who play though. It’s mostly middle and high school boys. A deviation of soccer, futsal, is more common with men in their twenties. There are lots of futsal clubs for adults and they’re always looking for new members to join.
Sumo is popular for the older generations to watch on TV. I’ve never met anyone under 45 who was interested in sumo, but it happens to be the national sport. It is pretty exciting to watch, and I would love to see a real bout. I hear it’s a great experience.
Football (American) and hockey are non-existent. People know what they are, but I haven’t met anyone who knows the rules or who has watched a game. The biggest presence football has in Japan is with the manga Eyeshield 21. I have no idea how well it’s represented. I’ve heard that there are private company football teams, but they aren’t well known by the public. Some high schools and many universities have a rugby team. This is not football though. Most people I’ve met seem to think rugby and football are the same.
Another interesting comparison: I lived in Halifax, Nova Scotia, Canada. It’s considered a medium-size city in Canada but is quite small in comparison to Japanese cities. The population is 375,000 people. However, there were many outdoor basketball courts in comparison to Japan. I can easily count ten within a bike ride range of my old house. Nagoya has a population of 2.2 million people, but I’ve only seen one outdoor basketball court. And it’s a half-court!
Volleyball is common with both boys and girls. Tennis is similar. Table tennis is a common after school club. Most middle schools and (I think) all high schools have a pool to teach swimming in PE. These schools will usually have a swimming club.
Golf is popular with a wide demographic. There are driving ranges all over, and some are open 24/7. You can see a lot of ojisan and salarymen practicing their golf swing with umbrellas while waiting for the train.
Oddly, martial arts are more common in the West. In Japan, judo is the most popular, followed by Karate. Kendo clubs attract members at the high school and university level. I don’t know any Japanese adult who practices martial arts. I know a lot of adults in Canada who do. My family has several black belts in tae kwon do and judo. I have a brown belt in Karate.