At the risk of repeating myself in every thread about urbanism, in asian megacities like Tokyo nature is a train ride away, at any time, any day. In Europe we've just been bad about planning and building infrastructure.
Only if you consider nature to be like a city park crowded with people. Real nature doesn't start at train stations.
We went mountain hiking every second weekend or so when I lived there. We always took transit.
We often went without seeing a single person once we got off the bus until we got to our destination (usually an onsen).