Like everywhere else, Japan does not yet have ideal facilities for people with a disability. However, great progress is being made and buildings are gradually being adapted to make them more accessible.
At crossings with lights, music tells you when to cross, and ticket machines in Tokyo generally have braille. Furthermore, more and more places are allowing free entry for disabled people and a carer.
Many Japanese towns have very narrow pavements which does not make getting around in a wheelchair easy, but they have tactile paving and road markings for the visually impaired. Also, the kerb is very low (or non-existant) between the crossing and the pavement.
In public transport there are specially adapted seats called yûsen-zazeki, near the doors, which are reserved for people with disabilities. In the case where a train does not have a level access threshold, station staff will provide a ramp within moments.
Modern buildings are more often than not equipped with access ramps and most buildings and stations have lifts.
The site Accessible Japan gives further information about travelling in Japan with reduced mobility.