Elementary school kids ride free on Kyoto city buses (normally kids are half adult fare) through 8.31 by saying “Eco-summer” to the driver when getting off the bus. This is good for up to two kids per group, so if you have a big group, make sure they sit apart and pretend not to know each other and maybe wear fake mustaches and trench coats. Kids under elementary school age always ride free.
Kyoto City buses are usually green like this one, although they are sometimes wrapped in full-body advertising that obscures the green. This campaign is not valid on private lines such as Kyoto Bus (brown and creme colored), Keihan bus (red and white) or others.