Jingū Baseball Stadium, built in 1926, is home to the Yakult Swallows, Tokyo’s number-two team (but number-one when it comes to fan loyalty; Swallows fans are famous for their 7th inning stretch routine). Get tickets from the booth next to Gate 9, open from 11am to 5pm (or until 20 minutes after a game ends), or online at www.yakult-swallows.co.jp/en.
Same-day outfield tickets can be had for as little as ¥1400 (¥500 for children); they're usually available, unless the Swallows are playing one of Japan's more famous teams (like the Giants).