The fundamental difference
MLB stadiums serve stadium food — generic items sold at inflated prices. NPB stadiums serve the local cuisine of their home city, prepared by actual restaurants, at prices that often match or beat the restaurant itself.
Regional identity
In MLB, a hot dog in New York tastes like a hot dog in Arizona. In NPB, food changes completely by city. Sapporo serves seafood and lamb. Hiroshima serves okonomiyaki and oysters. Sendai serves beef tongue. Fukuoka serves pork-bone ramen. Every stadium visit is a food tour of Japan.
Quality
ES CON Field has 30+ restaurants and an on-site craft brewery. MAZDA Stadium has BBQ terraces where you grill your own food while watching the game. Jingu Stadium has a craft beer selection that rivals dedicated beer bars. The best NPB stadium food is restaurant-quality. The best MLB stadium food is good-for-a-stadium quality. Different standards.
Price
NPB stadium beer: ¥800-900 ($5-6). MLB stadium beer: $12-16. NPB main dish: ¥600-1,200 ($4-8). MLB main dish: $10-18. A full NPB game-day meal (food + 2 beers) costs ¥2,500-3,500 ($17-23). The MLB equivalent costs $35-50. NPB wins on value by a wide margin.
Service
NPB has seat-side beer vendors who carry kegs and pour fresh draft at your seat. You raise your hand, they pour, you pay. No line, no leaving your seat. MLB has similar vendors at some parks but the coverage is less consistent.
Bringing your own food
Most NPB stadiums allow outside food. Most MLB stadiums restrict it. A ¥500 convenience store bento brought into an NPB game is a perfectly normal, accepted move.
How to buy NPB tickets
Official team sites or English-language platforms. Budget ¥1,500-2,500 for food and drink on top of your ticket.