Lotus root chips may not be traditional Japanese food, but they are easy to make alternative to potato chips.
Just peel a lotus root and slice it thinly with a knife or a slicer. Immediately soak it in vinegar water to prevent from discoloration. Pat dry the slices using paper towel and deep fry. Take out from oil when both sides of slices become golden brown, and remove excess oil on paper towel. Sprinkle salt while hot. If you make kale chips, you can make this at the same time.
Find out how to choose good lotus roots from here.