If you want to get a discount for people having some difficulties (Syogaisya- waribiki 障害者割引), you mainly would be asked if you have a Disable certificate (Syogaisya-tetyo障害者手帳.) at such as Disney Land, Universal studio Japan and so on.
Disable certificate is issued to people living in Japan. Travellers cannot get this certification, thus you could be hard to get some discount for people having difficulties. In the case that the facilities or amusement parks are not so huge, you might get some discount as long as you can proof that you have some difficulties.
You should try if you can get some discount at the ticket office any ways.
Disable certification (Syougaisya-tetyo 障害者手帳)
Disable certification is a certification that people having difficulties can get.
This certification is provided to people having some difficulties for daily life and working.
Disable certification covers people having physical diseases that can be seen as well as other diseases such as eyesight problems and blood diseases that cannot seen.