Awaodori

Every August, during the holidays, a large festival is held in Koenji.
Both North and South sides of Koenji station are decorated and spectator stands are erected.
The festival itself features a lot of dancing, singing/chanting and playing instruments-mostly drums.
Each dance group wears matching clothing and comes from all parts of Japan, as indicated by a banner carried by someone in the group.
Celebrations are held over three days and it's very busy and crowded.
Makeshift foodstalls are scattered everywhere.

Celebrations start in the mid afternoon.
Personally recommend spending a day in Koenji and come around 12-1pm and you will see a lot of people preparing and in full costume...good chance for pics just by walking around the station and back streets.
Coming early also gives you the chance to get familiar with Koenji and locate a good spot for later on.

The actual singing and dancing starts at 6pm and lasts for around 3 hours.
There are several start points around Koenji with the main attraction being close to the station.
Here is where it's most crowded and if you haven't come early enough, then you'll be watching it 3-4 people deep in the crowd.

Arriving at Koenji station anytime ater 5pm will take you a lot of time to navigate your way to a good viewing point...which you probaly won't get anyway as all the good spots will be taken.
Koenji station is relatively small with only 2 exits. On festival day, Koenji becomes a mass of bodies slowly shuffling their way to a good spot. Get here early, like I said.

Living in Koenji, I was able to find out where about 30 of the groups were starting their parade.
Head into the back streets for an in-your-face view.
I took those pics(see other posts) from the North side, about 3 minutes from the station where it seemed that all the locals knew of.
Come out of the North exit, and turn right towards the police box, and go acroos the crossing. Turn left after the crossing and walk past the pachinko parlour, and keep going. You should see "Jeans Mate".
It won't be too hard to miss as you will see the crowds. From there, be a bit adventurous and head into the back streets.
You'll get the best view and it's noisy as fuck.
There is no break from 6-9pm, so make sure you are stocked up on grub and beer. And of course, being in the summer, it's bloody hot and humid.

Awadori in Koenji is definitely a "must-do" activity in Tokyo.