MUST TO EXPERIENCE #7: roten(street stalls) at festival

Roten(露店) are open-air stands or street stalls that are set up during the days of a festival.

A scattering of small food stalls are erected on the temple grounds, and each one serves up its own specialty: okonomiyaki (savory griddle cakes), tako-yaki (octopus dumplings cooked in iron molds), yakisoba (fried noodles) and yaki-tomorokoshi (roasted corn) are regular mainstays. The smokes from food stalls make lively atmosphere of festivals.

Other popular stall foods include ika-yaki (grilled squid); ringo ame (candied apples); baby kasutera (small baked sponge cakes); crepes; jaga bataa (steamed potatoes with butter); and choco-banana (chocolate-covered bananas). Longtime favorites also include watagashi (cotton candy) and anzu ame (candied apricots).

Other traditional ennichi fair entertainment involves toys and games such as omen (character masks), shateki (shooting at targets), kingyo sukui (scooping up goldfish) and the ever-popular yo-yo sukui, where colorful water-filled balloons are fished from a pool. These games invariably attract clutches of enthusiastic children who happily spend their money to fish for small prizes.  (Reference: Kikkoman Corporation food forum)

Food usually costs around $3-5. 

There are hundreds of festivals during summer seasons. 

Festivals are often associated with temples or shrines, but there are also fireworks festivals etc.

Also during new year season, dozens of stalls are set up on the  temple grounds waiting for people's first shrine visit (Hatsumoude).

You should really experience lively atmosphere of Japanese street stalls at festivals.