Beware that more often than not, the sandwiches are not as filled as you'd expect.
https://soranews24.com/2020/10/23/7-eleven-japans-paper-tige...
https://www.youtube.com/watch?v=UHgIA1m3wNo
Most of the time they are.
There’s no magic. They’re just sandwiches that look pretty because they push everything to the very edge.