Japanese people would ever like milk and butter flavors, his 10-cen milk caramels became very popular in 1914. They were less buttery and more resistant to melting in hot Japanese weather than the caramel formulations that he had seen in the United States. To adapt chocolate for the Japanese market, where chocolate had a reputation for bitterness, Morinaga sold milk chocolate, with advertisements describing its flavor as "On behalf of modern Japanese tastes." In 1918, his company was the first to mass-produce chocolate in Japan. In addition to caramels and chocolate, Morinaga Mill also produced biscuits, drops, and milk-related products. Morinaga said that he produced several different products rather than one because the market for Western-style sweets was still small. Morinaga is considered one of Japan's greatest industrialists who was not part of a zaibatsu. Early difficulties of the company included the fact that Japan had little commercial milk production, obliging the company to open its own dairy. Another difficulty was that Japan had little arable land for crops and no locally produced corn or sugar cane to make corn syrup. Relationship marketing After Matsuzaki refused to let retailers sell competing products in the 1920s, Morinaga replaced contract-based wholesale agents with a sales company that Morinaga co-invested. The salespeople in these new companies worked with retailers to help sell products. This system was part of the keiretsu, or informal business group, that Morinaga was a part of. Morinaga opened its own western-style retail stores, complete with a display window and soda fountain. His network of exclusive retailers rose to 4,000 stores before World War II. The retailers had to avoid selling products similar to Morinaga's and sell Morinaga's products for certain fixed prices. Morinaga also created a society for sweets retailers to encourage the modernization of the industry, and gave illustrated examples of how to create a display window and modern floorplan. Morinaga's various vertical marketing campaigns included a special product available only on the 1st and the 15th of every month, a nationwide art festival using candy wrappers, and "special days" for member stores in certain regions. Inspired by Takashimaya's "mannequin girl", Morinaga hired five "Sweet Girls" to be demonstrators/models at events. The MB Club sent members candy twice a month and invited them to special events, in exchange for a monthly fee. The MB Club was one of the first club marketing programs in Japan. These practices showed