What is the number 1 snack in Japan?

I'm curious to know, what snack do the Japanese people consider to be their absolute favorite, the number one snack in their country? Is it a traditional Japanese delicacy, or has a foreign snack made its way into the hearts and minds of the Japanese people? And what makes this snack so beloved, is it the taste, the texture, or perhaps the nostalgia it evokes? I'm eager to find out, what is the number 1 snack in Japan?