It was a chocolate biscuit that turned Masayuki Iwasa, a self-professed penny-pincher with a sweet tooth, into one of Japan's most scrupulous chroniclers of "shrinkflation."

Having sworn off his favorite Chocoliere tartlets for a decade after Bourbon Corp. reduced the package size, the newspaper delivery man and part-time stock trader was spurred to action around two years ago after he noticed the biscuits had also gotten smaller.

"I was annoyed they were shrinking and shrinking," said the 45-year-old Iwasa, whose website, (price increases), documents surreptitious price hikes.