No, not a philosophical question about the work/non-work divide...more
of a practical and legal one.

What responsibility/authority does an employer in Japan have over an
employee, outside of their time at work? And in particular, does the
commute to work come under the authority and responsibility of the
employer? In the UK, it certainly does not, and (with some limited
exceptions) what the employee does in his own time - including time
spent commuting - is his personal business.

However, in Japan, it is common for commuting expenses to be paid (in
the UK this is very rare) so maybe the situation is rther different -
does anyone know for sure?

Note I'm not talking about business trips where the employee is
generally considered to be basically 'on duty' all the time, in the
UK.

James