If you are visiting Kyoto in summer, You don't miss the Gion Matsuri Festival!
It's one of the largest and most historical festivals in Japan.
Why don't you wear a Yukata (= kimono for summer. It's not expensive, easy to wear and washable!!) and hang out in the Festival!?
Gion Matsuri Festival Event Calendar

JULY 10-14
Hoko and Yama Tate (float construction): On these five days, the festival's 32 floats are assembled. No nails are used.
10
Omukae Chochin (welcoming lanterns): At around 16:30, men wearing
formal kimono and carrying long bamboo poles from which lanterns are
suspended, depart from Yasaka Shrine, heading west along Shijo to
Kawaramachi. 10
Mikoshi Arai (mikoshi purification): During the festival, the
deities of Yasaka Shrine reside in a temporary shrine called the Otabisho.
Before moving the deities on the mikoshi portable shrines, the mikoshi
are purified with water from Kamogawa River. The mikoshi depart from
Yasaka Shrine at 19:00 and arrive at the bridge at 20:00, then come
back to the shrine at 21:00. 12-14
Hoko Hikihajime & Yama Kakizome (trial pulling): On these
days, the people of each respective float neighbourhood try pulling
the newly constructed floats. 14-16
Yoiyama (eve of the grand parade): On the three nights before
the grand parade, the festive atmosphere reaches its peak. The streets
are crowded with people, many in traditional dress, Gion bayashi music
fills the air, and many stalls are set up along the main streets.
15
Traditional Entertainment Performance: On this day, at Yasaka Shrine, from 15:00 to 18:00, traditional Japanese entertainment (kabuki, biwa lute, harp, kyogen, dance, etc.) will be performed.
16
Iwami Kagura (ancient court dance): From 19:00 at Yasaka Shrine, ancient court dance will be performed to the music of flute and bells.
17
Yamaboko Junko (grand parade): At 9:00, the main Naginata-boko starts moving. When it reaches Fuyacho, the chigo sacred child on the float cuts the sacred rope and the parade begins.
24
Hanagasa Junko (flower umbrella procession): At 10:00, about ten large umbrella floats attended by nearly 1,000 people depart from Yasaka Shrine. Various dances will be performed.
25
Kyogen Performance: At 13:00, the Shigeyama Family will perform special kyogen (comical theatre) plays at Yasaka Shrine.
28
Mikoshi Arai (mikoshi purification): As on the 10th, the mikoshi are again purified on Shijo Bridge at 20:00 before the deities are carried back to Yasaka Shrine from their temporary home, the Otabisho.