Japan is a country which has local specialties throughout the nation. For example, monjayaki is Tokyo. takoyaki is Osaka, udon noodle is Kagawa prefecture and tonkotsu ramen is Fukuoka.
In addition to foods, there are local confectioneries throughout the nation too. Due to Japanese love traveling and also have many domestic business trips, there are custom to buy souvenirs to their families, friends, neighbors and colleagues. Therefore most of the people buy local confectioneries during the trips.
One of the most famous confectioneries of Tokyo are Tokyo Banana. It is a sponge cake filled with banana puree. The sponge cake is baked and then steamed. It appeared on the market in 1991, and it is the leading confectionery souvenir of Tokyo.
Tokyo banana can be bought at Tokyo station, Narita and Haneda airports. It is quite difficult to find in supermarket therefore if you are looking for Tokyo banana, check the kiosks in Tokyo station. There are several flavors, including seasonal limited ones.