Second class, also called "Ordinary" is of a very high standard - trains are clean and seats are generously sized, with plenty of leg room, especially on the Shinkansen bullet trains. Should you desire a little more luxury, then why not purchase a first class pass, giving access to the so-called Green Cars.
Travelling in First Class
The first class pass gives access to the Green Cars, located on most long distance trains. Advantages include large, 40° reclining seats with ample leg room. You won’t have to jostle for seats at busy times as the Green Cars are always uncrowded and quiet. Your personal crew even hand you wet towels and snacks on some lines. It’s especially great for those travelling with families or in peak season.