The 10th of the 24 Solar Terms 【Summer Solstice】(geshi)
　　

This is the time of year when the day is longest and the night is shortest.

As the kanji for "Geshi" literally means "summer arrives," the summer solstice marks the beginning of the full-fledged summer.
Temperatures rise, and the heat increases day by day, but from this point on, daylight hours will gradually shorten towards winter.

The Winter Solstice, when the sun's power is weakest, was considered the "sun's birthday" or the New Year's Day of the solar year, as it marked the beginning of days growing longer. The Summer Solstice, when the sun's energy is felt most strongly, was believed to be the time when its blessings reached their maximum.
For ancient peoples, the Winter Solstice was considered the "day closest to death," as the sun was hidden in the cold where crops could not grow, and it was the longest night of the year, shrouded in darkness. On the other hand, the Summer Solstice, where the sun's light illuminated the earth and nurtured crops, was seen as the source of human life and revered as a symbol of human activities such as men and women meeting and procreating. Archaeological excavations of ancient civilization sites have unearthed various ruins and petroglyphs (rock carvings) symbolizing sun worship.

Even today, in various parts of the world, there are many customs of "Summer Solstice festivals" that are based on sun worship from before the spread of Christianity. (Many of them have evolved into Christian festivals.)
Although the shapes and names differ, many of these festivals feature bonfires as a symbol, with fire festivals centered around dancing around the fire. They are held with gratitude to nature as the source of life that nurtures flowers and crops, as well as prayers for the prosperity of the people and the meeting and blessing of men and women.

In Japan, in addition to the Oyu Stone Circles (stone circles) and sundials from the Jomon period in Akita Prefecture, which remain as ruins, due to a long history and culture of nature worship, various legends remain at many shrines, palaces, and temples.

Amaterasu Omikami, famous at Ise Grand Shrine, is the sun goddess, Susanoo-no-Mikoto is the god of the sea and storms, and Tsukuyomi is the moon god. Gods have been believed to govern all things in nature.

Japan's "Summer Solstice Festival"　
　

The "Meoto Iwa" (Wedded Rocks) visible from Futami Okitama Shrine show the sunrise between the rocks only around the summer solstice. A purification ritual called "Misogi" is performed where people enter the sea, bathed in the sunrise of the summer solstice, when the sun's energy is strongest, between the Wedded Rocks.

Additionally, around the end of June, "Chinowa Kuguri" (passing through a茅ring) is held at shrines throughout Japan as part of "Nagoshi no Harae" (Great Purification of Summer).
The Oharai (Great Purification) is a Shinto ritual rooted in Izanagi-no-Mikoto's misogi-harai (purification ritual), and it was a ceremony to cleanse oneself of defilements and ward off disasters at seasonal turning points.

Twice a year (around the Summer and Winter Solstices), "Nagoshi no Harae" and "Toshikoshi no Oharai" (Year-End Great Purification) are held.

It is said that the reason why there are fewer Summer Solstice festivals in Japan (when the sun is at its fullest) compared to other parts of the world, despite the fact that the deity enshrined in Ise Grand Shrine, a particularly esteemed shrine in Japan, is Amaterasu Omikami (the sun goddess), is related to the rainy season.

The rainy season begins in earnest nationwide after mid-June. The continuous long rain and the fact that it is not a time when people feel the length of daylight hours are cited as reasons.

Even so, as a refresh at the turning point of the season, and because bodies unaccustomed to the heat tend to get tired both physically and mentally, there are practices like "Nagoshi no Harae" and "Doyo-no-Ushi" (midsummer day of the ox). These are cultures of cleansing the mind and body and getting the body in order as one goes through the summer, added at these seasonal junctures. This, I believe, is wisdom nurtured by the land of Japan.

The next solar term is "Shōsho" (Minor Heat).