@JuliusCV Banana is the most popular fruit in the world. Or technically tomato is, but it's often counted as more of a vegetable in the kitchen. I don't know about Japan specifically and I've heard various imported foods are expensive there, but since I also live in an expensive country, I doubt it's really significant from my pov. It would be surprising if banana wasn't relatively popular in Japan as well. Not to mention the Japanese are rich.
@Ifrittuccia
In the previous chapter their training was hellish and they were only given supplement and nutrition pills (effective but not tasty) to live on.
Then the odd duo found bananas and called the others over