In Kyoto, we have some confections exclusively available only during the Gion Festival (祇園祭り) season.
For example, the float called Uradeyama (占出山) sells a sweet cake called Kiccho-Ayu (吉兆あゆ, fish shaped pancake with gummy rice cake called Gyuhi inside) manufactured by Daigokuden-honpo (大極殿本舗) only from July 14 to 16.
Among many other, the most famous one is Gyoja-mochi (行者餅) manufactured by Kashiwaya Mitsusada (柏屋光貞) available only on July 16. This cake has a story which shows a deep connection with Enno Gyoja Yama (役行者山) float: long time ago, the owner of Kashiwaya Mitsusada dedicated Gyoja-mochi to the deity of Enno Gyoja Yama float, and people who ate the cake after the festival stayed healthy for a long time, hence, this cake is said to be beneficial for healthy life and longebity. The cake is made of three layers, a Gyuhi cake, Japanese pepper seasoned white miso (味噌) sauce, and a crape.
It's very precious becuase it's avalilable only on one day a year. If you haven't had it before, please try!