If you should happen on a local matsuri in Japan

Every city has them, even down to the smallest villages: the local festival, or matsuri.
Like in Germany, where the Schuetzenfest changes the city and engages the village elders in the planning for a year in advance, if not longer, the local people participate in the organization. It is often the biggest local event in the neigborhood and the biggest party of the year.

Normally the matsuri is held on a weekend, starting on Friday evening, with the main festivities on Saturday, because traditionally celebration in Japan, of whatever kind, involves a great deal of drinking. So a few days before, either in the shrine or a bearby public place, the mikoshi comes out and with it a stand showing off the neigborhood donations.
Mikoshi is usually translated as "portable altar", but it is not really an altar in the Western religious sense, it is the home of the god - spirit may be a better translation - who actually moves into the little shrine and is carried among the street of the neigborhood, to bring its blessings to the people who live there.

oneThe matsuri is usually a benefit for the local shrine, although buddhist temples have also been holding them of late - with a more educational twist, featuring their flower or formal gardens, or outdoor cinema (bring insect repellent), or concerts by Indonesian Gamelan orchestras. But it is not unusual for the matsuri procession carrying the mikoshi to end at the nearby Buddhist temple, one reason being that the Buddhist sects in Japan have an active group of volunteers helping out, serving the men (usually they are men) drinks after the sweaty work of carrying the heavy mikoshi.
As a benefit, it is of course dependent on donations. Next to the portable shrine (the mikoshi) there is a booth to recieve collections, and to show them off. The donations are either money, in-kind donations (like the local dry cleaner taking care of the jackets that festival participants wear), or they are food and drink - Japanese spirits, whether they are spirits of the dead or spirits of a mountain, like their food and especially drink.
One detail worth pointing out is the mirror in the middle of the display. It comes from the shrine, and it is the centerpiece of the display on the altar there too. Look into it, and you will see the face of a god.

The local shrine is where the festival takes place. Usually the shrines and their surrounding gardens, oreven forest, is a serene and contemplative place. The spirits that inhibit Japanese shrines are nature spirits and they appreciate growing things surrounding them. Perhaps that is why they often double as the playground of children from nearby daycare and kindergarten, although that sort of degrades the serenity of the place.
But it not only means the shrines have a small park attached to them, it also means they have open space available. Which is why the shrine grounds are usually where the festival takes place. Or at least the corporeal part of it.

Apart from the spiritual part of a matsuri, where the mikoshi is carried around the neigborhood, there is a part much more aimed at the body than the spirit. Temporary stands are set up in the grounds of the shrine, featuring traditional Japanese comfort foods and traditional activities.

when the Friday evening comes, it is time for the matsuri to start. It is not just about the marketplace and the mikoshi, it is also about the local community participation. In this picture, the priest of the local shinto shrine blesses the participants of the festival. It may be hard to tell from the picture, but the people are all local businessmen and business leaders, investing their time and the company resources to bring the local community together.

But while the mikoshi is a huge thing, requiring quite a bit of brawn to carry around, there is also a childrens version. The childrens mikoshi is a scaled-down version of the adults', with the same ornamentation but less than a third of the size but weighing a lot less. That does not mean it is a toy, though. It is carried around the city with the same solemnity and calls of "wa-shoi, wa-shoi!" accompanied by the same fllute-and-drum music. Almost the same distance, if a different path, than the adult version.

The smaller children do not have the body strength as their brothers (and, best to add, sisters) who carry the mikoshi, but they get to pull the taiko drum that acvompanies the flute music. This is the drum you may have seen in TV shows featuring Japanese drumming, and it has a really deep and booming tone - but can be stroked to call out that tone in an almost whispering voice.
Not that the children do. They are more about maximizing the booming, not always rythmically, so perhaps the homeowners along the route are happy that the childrens mikoshi and the taiko drum are processioned during daytime.

The arrival of the mkoshi at the shrine the first night marks the start of the matsuri that most people will care about - because this is when the celebrations will start. The market stands open and even if there is a long line of people at the doors of the shrine, praying is not what the matsuri is about.

A matsuri is about eating, drinking, and making merry. Especially drinking and eating. Festivals today are the only places where you can find traditional Japanese food like grilled aji.

But festival foods also include traditional Japanese comfort foods like takoyaki (fried dough balls with a small piece of octopus meat inside), and okonomiyaki, which usually contains cabbage, but literally means "what you like fried", a dish that has entered haute cuisine and is served in upscale restaurants, but had its origins during the meagre years after WW II, when there were few things to eat and even fewer things to fry.

The merry-making part is not just relegated to providing lots of (actually very expensive) alcohol. Many festivals provide entertainment, often local talents performing songs and dances.

A festival also means a chance to dress up in the traditional summer costume, the yukata, and show it off to friends and other festival goers.

But a lot of the entertainment is provided by traditional activities. Fishing for goldfish with a paper sieve that is designed to break after a few minutes is one. A shooting gallery with cork guns may be another. There will be several lotteries, even if the prizes may be more aimed at children than grownups, however merry they may be.