Luggage on Shinkansen
We have just finished our Shinkansen trip and I wanted to let anyone who is worried about luggage size know- EVERYONE including Japanese travelers just takes their full sized suitcases onto the train and puts them in the overhead shelf!
I was so worried about my cases that I very nearly used a transfer service. Unless you decided to bring your entire house with you, you DO NOT need to purchase oversized storage or use a transfer service.
The storage above the seats is massive! It is not at all like an airplane - there is no door covering it etc. and it easily accommodated my full sized case.
Definitely reserve a seat using the online service if you can. That was super helpful, but seriously - the paranoia about luggage is overblown in my experience.