In the year 1852, Keisuke Ito was already in his 50’s but he wasn’t done with the medical field just yet. In fact, it was the year that he produced his best work in the form of a smallpox vaccine. It was that year when he was given an order by lord of the Owari clan to have a look at the methods for vaccination that were used to deal with smallpox which was a big problem in the world and in Japan. Keisuke was up to the challenge and came up with a special vaccination method for use in Japan and despite all his studies and books, it was the development of the vaccine that became known as one of his best works and his greatest achievement in his medical career. As part of his work for the Lord, he contributed medical treatment in the area o Owari and even worked hard to promote the natural sciences in the area.