The short answer: most stadiums allow food
Unlike many American and European venues, most NPB stadiums let you bring your own food. The main restriction is on drinks — cans and glass bottles are universally banned, but PET bottles (500ml) are usually allowed.
Universal rules (all NPB stadiums)
Allowed: PET bottles (500ml or less, with cap). Bento boxes, onigiri, sandwiches, snacks. Portable chargers. Cameras (no flash). Banned: cans, glass bottles, outside alcohol, tripods, selfie sticks.
Stadium-by-stadium
Tokyo Dome (Giants)
Food: yes. PET bottle: 500ml with cap. Alcohol: no outside alcohol. Bag check at all gates.
Jingu Stadium (Swallows)
Food: yes. PET bottle: yes. Alcohol: no outside alcohol. Buy craft beer inside — it's worth it.
Koshien (Tigers)
Food: yes. PET bottle: yes. Jet balloons: yes (unique to Koshien). Alcohol: no outside alcohol.
ES CON Field (Fighters)
Food: yes, but with 30+ restaurants inside, you won't need to. PET bottle: yes. Alcohol: no outside.
MAZDA Stadium (Carp)
Food: yes. PET bottle: yes. BBQ terrace users bring their own ingredients in some cases — check specific rules.
Yokohama Stadium (BayStars)
Food: yes. PET bottle: yes. Rain poncho recommended (outdoor, no umbrellas allowed).
Budget strategy
Convenience store bento: ¥400-600. PET bottle tea: ¥150. Total: under ¥800 ($5). Buy one beer inside (¥800-900) for the experience. Total game-day food cost: under ¥1,700 ($11). That's a complete meal at a professional sporting event.
How to buy tickets
Official team sites or English-language platforms. Pack your food, grab your ticket, and enjoy Japanese baseball the budget-friendly way.