Shinjuku Station’s NEWoMaN area at the South Exit, inside of the JR station, has the only branch of Wa’s Sandwich. Wa’s Sandwich’s egg salad is made with mayonnaise, shio kōji, and sweet Saikyō miso, perhaps Japan most Japanese sandwich? The seasonings are light, so it’s hard to perceive. But, the bread is a very good quality. It’s not cheap, at 500 JPY. But it’s a big sandwich with thick-cut slices of pan de mie. Next time I go back I’ll try one of their other sandwiches. There is a colorful selection to choose from.
To put things into perspective, Japan’s famous egg salad, from 7-11, is a reasonable 220 JPY.
Wa’s Sandwich
Shinjuku Station NEWoMaN at Shinjuku JR South Exit (inside the station)
Food Sake Tokyo 
I’ve had it—it’s delicious, but not as delicious as 7-11. 🙂
At that price you would think it’s twice as delicious as 7-11. Hard to beat 7-11 on sandwiches!