In June 1955, countertops in Tokyo and Osaka drugstores were buried in "Ichoyaku Marin", a new medicine for stomach and intestinal problems. Two or three times a day, Kobayashi Daiyakubo salesman would visit, and each time bring Marin, ask about sales, and urge shopkeepers to expand provisions for the medecine. In one shop the counter was full of Marin, and the owner would help customers, looking out from between mountains of Marin.

Head office at Kobayashi Daiyakubo was overflowing with battlefield-like energy. Saburo Kobayashi was like the head of an army, scolding and encouraging his employees, tenaciously on the phone, always urging and requesting the pharmacies to encourage sales. Marin's advertising was also increased markedly. Not only was it in the newspapers, but radio was widely used for advertising. Marin became a radio sponsor, and Chiyoko Shimakura, at the time of her debut, also took a role in an advertisement. Marin was the first new product that Kobayashi Daiyakubo had bet their fortunes on since its establishment.

It wasn't that Kobayashi Daiyakubo did not have other similar medicines. They made "Kobayashi Isan," "Hiotamin" and several others. Marin was reformulated based on know-how from these products, and with a modern name and packaging, was planned to be their epoch-making new product. Furthermore, it was the first medicine developed after the war by the Kobayashi manufacturing devision. With the success of this product, Saburo Kobayashi was hoping to bring the manufacturing group up to the level of the wholesale group.

The development of Marin was Saburo's project, and his factory manager, who was a pharmacist, helped him with it. Initially the product name under the Ministry of Health and Welfare Permit was "Marin", but customers could not tell what it was for, so they applied for a name change to "Ichoyaku Marin", indicating its use, and received the new permit the following month. It was a very effective product, and there was plenty of advertising. The whole company was behind sales, but Marin's life span was short. In addition to the market for this sort of medicine being saturated and there being several other strong rival products around, Marin had an unexpected flaw for which it was forced to withdraw from the market. The formula for Marin would later be improved, but at the end of 1958, production was suspended.