Yakult is a probiotic milk drink created in Japan and now sold in 31 countries. It contains Lactobacillus casei bacteria strains and is marketed in 65mL bottles. Minoru Shirota developed the first version in the 1930s by fermenting milk with L. casei. Yakult has since expanded its product line and uses its probiotic research for cosmetics. It relies on a unique door-to-door distribution system called the Yakult Ladies to educate customers and promote the health benefits of probiotics.