Japanese sandwiches are my go-to meal when I am on the run, even before onigiri rice balls. Meruhen is my favorite sandwich shop and if I am not near one, then some of the convenience stores like 7-11, Lawson, or Family Mart, also has great sandwiches.
The sandwiches are built on crustless pain de mie (white bread). Savory fillings can be egg salad, tonkatsu, ham and cheese, kabocha with mayonnaise, and more. The sweet sandwiches are fresh fruit with whipped cream, which I have a hard time swallowing. My favorite is the simple julienned carrots with a bit of mayonnaise, but you have to go early. It’s popular and is often sold out by the time I get there. The sandwiches are in the 300 JPY range.
Meruhenk branches in popular areas (there are many more):
Tokyo Station eCute 1st floor (inside the station) – with limited seating in the area.
Shinjuku Takashimaya, Shinjuku Odakyu
Daimaru Tokyo Station
and many more!