[Nathan]

Originally Posted by YuriTokoro

"Bon/Obon : August 8, 2009"

Obon, also known as Bon, is a Japanese Buddhist custom for the spirits of our ancestors. It is held around August 15 in many areas in Japan.

I would modify it even further:
It is held around August 15 across Japan.

"Across Japan" means that the festival is celebrated in many different places in Japan.

The main custom of Obon is visiting the graves of our ancestors, but after that it depends on the area.

In many areas, they make a horse and a cow called “shouryouuma” with a cucumber and an eggplant to welcome the ancestors. 'Shouryou' means spirit, and 'uma' means horse. They are the spirits’ conveyances between the afterworld and this world.

The cucumber means a horse which runs fast, and the spirits use it when they come, wishing they get to this world at an early hour. The eggplant means a cow which goes slow, wishing they go back to the afterworld late.

We know that a horse is fast, and that cows are slow, so you can leave that information out.

I would write these two sentences like this:

The cucumber, representing the horse, is used by the spirits to arrive quickly. The eggplant, representing the cow, slows the spirits' return to the afterworld. This lets the spirits maximize their time with us.

However, there are many people who don’t visit the graves or participate in the ceremonies. They go on a a trip because many companies are closed around Bon, and they think it’s very good opportunity.

"and they think it’s very good opportunity" could be rewritten:
and they take advantage of this opportunity

Almost 50,000 people departed from Narita Airport today. Like Golden Week, all leisure venues and almost all Shinkansen trains are full of people. Expressways are full of cars, and plane tickets are more expensive during bon.
You should avoid coming to Japan during Bon.

Thank you.
Bon Festival - Wikipedia, the free encyclopedia