It's so big, it's held two times a year rather than just annually. It is held at the biggest convention facility in Japan, Tokyo Big Sight. And it is basically one big Artist's Alley, where people sell their self-published manga and art. What is it? Comic Market, or what most people call Comiket. And it is the biggest manga fan event in the world. 2016's Summer Comiket, the 90th, took place August 12-14. Comiket 91 will take place December 29-31, 2017.
Summer in Japan: Hot Times and Family Memories
Long before the advent of air conditioning, which is pretty much ubiquitous in Japan, the Japanese people needed to learn to cope with their hot, sticky Summer climate. To that end, the whole period is liberally scattered with outdoor festivals. When it's too hot to sleep, you take your mind off of the misery by going to visit shrines, temples, and town squares, where street food, drink and dancing help make the hot season bearable. The traditions have held to this day.