It takes the right policies and a lot of time. We have seen American cities become less walkable and more auto-centric in the last ~60 years thanks to policies designed to hollow out urban cores and increase suburban sprawl [1]. We have also seen Amsterdam embrace "human-centric" urban planning, leading to significant transformation toward the vibrant, walkable, bikeable city that Amsterdam is famous for being today [2]. If American cities want to be more like Japanese cities, they can start by looking at the policies that make them possible, such as the relatively-sensible Japanese zoning laws [3].
[1] http://iqc.ou.edu/2015/01/21/60yrsnortheast/
[2] http://sustainableamsterdam.com/2015/12/livable-cities-campa...
[3] http://urbankchoze.blogspot.com/2014/04/japanese-zoning.html