Arrive early
Gates open 60-90 minutes before the game. That time isn't dead time. It's part of the experience.
Free things to do
Watch batting practice
Players warm up on the field before the game. You can watch from your seat or the concourse. At some stadiums, outfield fans can catch home run balls during BP.
Mascot performances
NPB mascots are a level above what you're used to. They dance, interact with fans, ride scooters, and have elaborate pre-game routines. Every team has at least one mascot, and some (like Truckun from the BayStars) have massive followings.
Walk the concourse
Japanese stadium concourses are designed for exploration. Food stalls, team history exhibits, photo spots, and views from different angles of the field. ES CON Field has a full "F Village" to explore outside the stadium.
Pre-game ceremonies
First pitches, national anthem performances, and sometimes full pre-game shows are free entertainment from your seat.
Cheap things worth the money
Gacha machines (¥300-500)
Capsule toy machines near stadium entrances dispense team-themed keychains, pins, and mini figures. Random selection adds a gambling element. Highly addictive.
Stadium stamp rally (free-¥300)
Some stadiums have stamp collection points. Visit each station, collect stamps, and receive a small prize. A fun activity for kids and collectors.
Cheering megaphone (¥500-800)
The plastic bat-shaped noisemaker used by fans. Cheap, fun, and a unique souvenir you can only get at Japanese ballparks.
Buying tickets
All of this is included with your game ticket. Outfield unreserved seats start at ¥1,500 ($10). The pre-game activities alone are worth the price.