i've found another worst skatepark at sagamihara kanagawa.
http://www.commotionworld.com/areaguide/actionsport/kanto/kanagawa/oyamapark/
the discussion with a old man; keeper of the public skatepark:
me "this is a kind of bmx. no problem."
keeper "scooter is dangerous! i don't allow it!"
m "i think bmx is more dangerous."
k "that is designed for skatepark!"
m "most of the inlineskates are not designed for it, but you allow them."
k "this park allows skateboard, inlineskate and bmx! that's all!"
m "then how about freelineskates?"
k "it is a kind of inlineskates!"
m "then scooter is a kind of bmx too."
k "eh... freeline is not a kind of inline, but a gear for use in skatepark!"
m "this park allows only three items, you said."
k "anyway i don't allow scooters!"
he should retire and be cared.