The bento sold at train stations are called ekiben. They are located inside of Tokyo station.
There is the Ekiben collection shop in the Tokyo Station. They have over 170 ekibens, while in Tokyo station, you can buy local ekiben here.
These are the samples. very beautiful!
There are many Ekibens such as seafood ,sea bream rice etc.
There is a live kitchen (demonstration kitchen) in the store,so you can buy warmed lunches box.
Among the approximately 170 kinds lunch box, “beef right in the middle” (1,150 yen) is the most popular .
Other popular one are below.
Shrimp Senryo flyer (Niigata) 1,300 yen
Komachi lunch (Akita) 1,300 yen
Shenzhen rice (Tokyo) 900 yen
Torimeshi (Takasaki) 900 yen
Dharma lunch (Takasaki) 1,000 yen
100-0005 Marunouchi, Chiyoda-ku, Tokyo 1-9-1 JR Tokyo Station premises