An eco-ride light train system will be tested in October that would fall in-between the heavy subway system, and buses and taxis in the public transportation system.
Who Soc'd It?
Personally, I would rather see Tokyo focusing on improving bike commuting conditions as the city is relatively small and flat. For example, it only takes 25 minutes to cycle between Shinjuku and Tokyo stations. If there were less annoying red lights and less obstructions on the road and an actual bike lane, I could make that ride in 15 minutes.
Japanese already use bikes for getting around their neighborhoods, so it would seem a natural step to take that to commuting to work.