It's a cosplay type of day. I always enjoy checking out the cosplay from Comic Market aka Comiket as I'm sure you're more familiar with it being called. The reason being is that it usually brings out some of the best costume to check out. Great job to Netageo. https://www.youtube.com/watch?v=YDz-csBuMec#t=285

https://www.youtube.com/watch?v=JSdUA31SWDI#t=156

Source