JR500, you need this: https://twitter.com/R_esculenta/status/668710688739557377
According to the tweet, he built them himself. Excellent work.
I think the event was the Surutto Kansai Bus Matsuri: http://www.surutto.com/bus/ https://ja.wikipedia.org/wiki/%E3%82%B9%E3%83%AB%E3%83%83%E3%81%A8KANSAI%E3%83%90%E3%82%B9%E3%81%BE%E3%81%A4%E3%82%8A
Looks like it's held mid- to late-September every year, with 27 companies participating in 2015. Attendance isn't indicated, but it's been significant for previous years.
How is it that a bus festival can draw 30,000 people? What makes Japan a society that's not just willing to use public transit, but is in some ways enthusiastic about it?