I hadn’t heard about this origin story of Japanese KitKat before and looked it up. Kitto katsu! means "you will surely win" or "you will surely succeed". So i

I hadn’t heard about this origin story of Japanese KitKat before and looked it up. Kitto katsu! means "you will surely win" or "you will surely succeed". So it is given as tokens for success in exams and the like. Katsu for winning/succeeding also can be seen in Tonkatsu = pork cutlet (katsu is the Japanese "shortening" of cutlet), which is also offered as a success token.