There are many fesitvals and holidays that are observed in Japanese culture and society. Many of them are similar to some Western holidays, though most of them stem from religious sources or from ancient traditions. These are not in any order at the moment.
Mid July or Mid-August for a week, ending on August 16th. In Tokyo this festival is celebrated in July instead of August.
O'bon is the time when, according to Buddist belief, that the spirits of the dead return home for a time. During this week long fesitval, families of Buddhist belief clean house and on the thirteenth of August go to the family graves, pouring water of the gravestones as well as the lighting of incense and lanterns and the leaving of flowers on the graves. After this visit the family returns, escorting the family spirits back home and to the family altar for three days. During this time, they prepare a special meal for themselves and the family spirits as well. After three days time more ceremonies are performed and the spirits are sent back to the heavens.
During this time many people return home and take part in local festivals where all dress in traditional Japanese attire. For three nights the people gather and dance in a circle around a platform covered in lanterns. Both men and women wear thair yukata (summer kimono), the men in colors of white and navy blue and the women in all colors. During this time there are also booths that sell a variety of items to enhance the festive atmosphere. At the end of this festival fires are lighted and lanterns set afloat in the rivers.
In Kyoto this festival is ended by another traditional event called the Gozan no Okuribi. This is the lighting of fire atop a series of mountian sides in the form of five different Kanji. Mt. Diamonji is the center of the attentions. These fires are lit to help the spirits to return to the heavens. This event takes place on the sixteenth of August.
Pictures of Gozan no Okuribi
This is one of the most important festivals featured in the series, though we never really see it being celebrated, we do see many aspects of it which help to give us dates for important events in Kenshin's life. It would almost seem as if all major events in his life happen around this festival or the date of August 16th. There are two times that Kenshin 'crosses paths' with this festival or the date.
In episode 62, while trying to convince Kaoru to stay in Kyoto a few days more, Okina mentions that they should stay to see the Diamonji Bonfires. The bonfires take place on August 16th, and we can place this episode a few days before that date. Also, it is during this episode that Kenshin visits Tomoe's grave for the first time in ten years. It is my thought that this episode takes place on the thirteenth, though I might be wrong and only wishing for that, as this date is the day that families visit the graves of their loved ones during O'bon. It would be fitting for Kenshin to visit Tomoe's grave on this day and a nice touch to the depth of his love that he still holds for her.
In Tsuioku Hen, we see this festival as well and can place the date of August 16th to a certain moment in the series. It is on this date that Himura the Battousai returns to Kyoto after his time in Otsu with Tomoe. During his return we can see Mt. Diamonji blazing with its Kanji for the festival/bonfire.
Autumn
Autumn festivals take many forms and shapes in Japan. Each location has their own traditions for these festivals but most have their backgrounds in the festival being in celebration of the harvest. Most of these are sponsored by local shrines and involve parades of mini-shrines and people dressed in traditional clothing as well as music and dancing. Below are a few more festivals celebrated during autumn in different regions.
October 22
One of the additions to the matsuri to make it unique or spectacular.
A three day festival in Nagasaki at the Suwa Shrine.
A three day long festival at Nagasaki's Suwa Shrine. This festival is filled with dances of Chinese orgin.
Autumn
Another autumn festival in which the celebrators 'fight' and 'argue' with each other in order to gain supremancy.
Autumn
A parade in Karatsu that is filled with floats of lions and modern story book characters.
October 22 in Kyoto. This is one of the many autumn festivals celebrated around Japan and is one of the better known ones.
This festival began in 1895 and is recalling of the history from the Heian time period to the Meiji Restoration. The people of Kyoto parade from the Imperial palace to the Heian Shrine, a three hour walk, portraying people from the multiple time periods. It's a unique celebration of Japan's history.
Tokyo two of three times in November.
Not really a festival in a sense, this is a time when the people in Tokyo (Tokyoites) are reminded of the coming New Year and can buy Kumade, good-luck bamboo rakes to ensure their luck for the coming year.
Early autumn in Tokyo.
A time when people of Tokyo can buy Chigibako, three toy boxes, as well as fresh ginger.
November 12 at the Myoren-ji Temple.
I'm not sure about this festival, except that it appears to be similar to the Shichi-Go-San children's festival. The festival is in honor of Holy Priest Nichiren and is a procession of children. Girls are required to wear traditional atire while the boys can wear Western clothing. Who was Priest Nichiren? I'm not sure everything I've found says he was a writer of religious text. If anyone has anymore information you can send it to us.
November 15th.
This is another old festival dating back over four hundred years, though over time the festival has changed. The modern festival as we see it today was established during the Edo period. This is a festival for children of the ages of seven, five and three and is a little akin to a 'rites of passage' for the children of those ages. Children are taken by their parents to the shrine at these ages to offer thanks and to obtain a blessing for the future for their children. Most traditional families have their children dress in traditional atire, though sometimes modern attire can be seen as well.
Why the ages of seven, five and three you might be asking? These are considered to be critical ages in development. In Japan children are considered 'gifts of God' until the age of seven. It's at this age they become normal humans. When a girl reached the age of three her hair would be placed in an adilt fashion for the first time. At seven she would be given her first obi. The boys at the age of five would be given their first hakama to wear.
To my knowledge we never see any autumn Festivals in the series.