ekiben

Hi,
The stores are not open 24/7, since the stations are not running 24/7. Opening times vary location. However, there are always some convenience stores near bigger stations (7-11, Lawson's, Family Mart, etc) that are open 24/7 and they have microwaves to heat up a bento if you like.

Your last question does not make much sense. You can do the above if you want to eat a heated meal while on the train. If you want to eat when you arrive, then go to the station store or convenience store after you arrive.

Good luck.

Thank you so much Toraneko....the last question is with regard to Tateyama Kurobe trip....heard people said that the food along the route is not nice and pricey....so thought of bringing food from Shinjuku and heat there when needed....:)