Ah, this one's a nostalgic treat for me. I had my first Tokyo Banana almost a decade ago when my Japanese colleague came and brought this with him. I absolutely loved this soft cake with banana cream filling. It's just like eating banana - shape and taste wise.
Nowadays Tokyo Banana has various filling flavours, like you can see from below :
Left - Original (banana cream filling);
Middle - Cat pattern (caramel filling);
Right - Giraffe pattern (banana caramel filling)
Each cakes is wrapped in individual plastic wrap. The pattern ones has each animal printed on the packet.
I once saw a Cheetah pattern on websites, but I couldn't find that one on my trip.
Shopping Tip :
It's not easy to find the pattern ones, so buy whenever you see them. I bought the Cat & Giraffe at 2 different stores in Tokyo Station. Don't expect to buy last minute at the airport, except the original which are available there.