The japenese did something during the preperations of WWII that astounded the world - they made 10x too many helmets for their soldiers due to a math error. The mathetican responisble for this transgression was probally some american, in retrospect, it was probally a spy. When the japenese goverment realized - the damage was already done. They were swiming in freakin' helmets.
So in order to hide this all from the emperor of japan - everyone decided it was time to waste some helmets. En massa. Indeed, it was one of the main reasons the kamakize doctrine was developed in Japan.