Tanabata

Tanabata (七夕) or the star festival, is a summer holiday in Japan that takes place on the 7th of July or 7th of August, depending on the region.  The festival is derived from an old folk lore that tells the tale of a farmer who found a lost robe belonging to the goddess Orihime.  She confronted him about it but he told her he did not have it.  The two fell in love and married, siring a number of children.  Later she noticed the robe, exposing the long hidden lie.  The farmer begged his wife's forgiveness.  She relented and said that if he buried 1000 sandals under a bamboo tree she would forgive him.  He was unable to accomplish the goal during his life time.  The festival associates the two lovers meeting again in the heavens with the nearing of the stars Altair and Vega.  A common practice for observing Tanabata is to write a wish on a piece of paper and tie it to a bamboo branch.

    Tanabata doesn't feature prominently in anime, as other aspects of Japanese life do, but there are some series that have dedicated episodes to it, most notably NANA.  Historically Tanabata and Obon would over lap so many locations tend to merge the two traditions in one large festival.  Obon definitely has made an impression in the anime world as it is frequently featured, being one of the most important holidays in Japan.