No one has ever written a complete history of the Unitarian Mission to Japan. For the purpose of this first attempt, I have divided its development into three overall periods: the first period, between 1887 and 1900; the second, between 1900 and 1909; and the last, between 1909 and 1922. 　　The official history of the Mission ended when the Japanese Unitarians wrote to request the American Unitarian Association (A.U.A.) to “close up their mission work in Japan” in March, 1922, and then ceased to hold meetings by themselves, several months later. But we should add one more period as an appendix to its history, because some of the remaining Japanese members restarted their activities after World War II. 　　At the start of each period, the outlook for the Mission seemed promising. But each time the results failed to fulfill the initial expectations. This paper is an attempt to clarify the causes of these successive disappointments.　　Unitarian activities in Japan began in 1887, when Arthur May Knapp was commissioned by the A.U.A. in answer to requests from some prominent Japanese. Knapp was warmly welcomed by many Japanese liberals, such as Fukuzawa Yukichi and Yano Fumio. He was also enthusiastically received by some government leaders, including Mori Arinori and Kaneko Kentaro, as a messenger for a new kind of a religion based on science and advanced philosophical thought.  Convinced that Unitarianism would flourish in Japan, Knapp went to the U.S. in 1889 to report his findings. Five months later, he returned to open an official mission, accompanied by Clay MacCauley, as a missionary colleague, and W. J. Liscomb, Garrett Droppers, and J. H. Wigmore. The last three had all been invited to work as professors at Keio University, but were also appointed assistants to the Mission. In the following year, H. W. Hawkes joined the Mission from England as a volunteer worker, and several months later, Kato Satori, previously a Presbyterian preacher, became the first Japanese Unitarian minister. Thus, their first church had already been established by October, 1890. The future of the Mission looked promising.　　However, a series of misfortunes befell them. First, Mori, Yoshida Kiyonari, and Nakamura Masanao, all influential supporters, died in the few years between 1889 and 1891. The Marquis Tokugawa was forced to yield to family pressure and desert them in March, 1890. This was owing to the strong anti-foreign reaction against the “unequal” treaties. From that time on, even Kaneko became hesitant about his links with the Mission. Secondly, Knapp had to return to America, on account of failing health. As a result of his sociable character, he had been “able to secure the cooperation of influential Japanese”, but MacCauley’s unsociability destroyed these links soon after Knapp left. Thirdly, MacCauley’s undiplomatic handling of the matter of Kato Satori caused the latter to publish a libelous newspaper article against the former. Thus, the Mission’s prestige suffered a severe setback. A lot of people left the Japan Unitarian Association (J. U. A.). This was the first crisis of the Mission. 　　Nonetheless, the Mission was able to recover its reputation in a few years by making a fresh start as a non-Christocentric free faith movement. Saji Jitsunen, an ex-Buddhist priest, and Kanda Saichiro were appointed as president and secretary. The “Jiyu Shin Gakko” (School of Liberal Theology), later renamed “Senshin Gakuin” (School for Advanced Learning), was established, and the  completion of “Yuiitsukan” (Unity Hall) was celebrated in 1894. The Association magazine, originally called “Yuniterian” (Unitarian) and then renamed “Shukyo” (Religion), joined with “Rikugo Zasshi” (Cosmos) in 1898. This had been founded by mainstream Christians including Uemura Masahisa and Kosaki Hiromichi, but now became the main J.U.A. periodical. 　　In 1900, MacCauley left Japan, and soon after the second crisis occurred. MacCauley had been confident that the Japan Mission could continue without any local representative from the A.U.A. Since competent persons such as Abe Isoo, Murai Tomoyoshi, and Kishimoto Nobuta had joined the J.U.A., he thought that the mission should be transferred to its direction and care. A new committee made up of seven Japanese members was therefore established to take care of the organization in 1900. A few years after MacCauley returned home, however, Saji, persuaded by Kanda, abolished the committee, leaving all power in the hands of the president and secretary. Outraged by their autocratic behavior, Abe and other leaders left the Association. Several years later, to make matters worse, Saji and Kanda began to quarrel over leadership. The Japanese Unitarians were in danger of splitting. The A. U. A. sent MacCauley to settle the matter in 1909. He sided with Kanda, declaring that Unitarians should be Christians, and that Saji was not the right sort of leader.　　A third of the congregation opposed MacCauley’s decision, regarding it as one-sided and arbitrary. They seceded with Saji and his assistant, Hiroi Tatsutaro. On the other hand, hearing that Saji had left, most of the former leaders, including Abe, Murai, Kishimoto and Toyosaki Zennosuke, returned. In 1910 the Association changed its name to the Tokyo Unitarian Church, and in the following year Uchigasaki Sakusaburo moved from Ebina Danjo’ Hongo Church to become their pastor. Other members of the Hongo Church, including Suzuki Bunji and Imaoka Shin-ichiro, followed Uchigasaki, becoming Unitarians in the same year. The name of the church changed once more, to Toitsu Christian Church. In  1912, Unity Hall was the site where Suzuki Bunji started the first Japanese labor movement, “Yuaikai” (the Friendly Society). “Ki-itsu Kyokai” (the Association Concordia) was founded in 1913 by “cultural people”, including MacCauley and Uchigasaki, working for cultural betterment and inter-faith harmony. The Japanese Unitarian movement looked full of promise again.　　After a while, however, like Emerson and Abbot, radical leaders of the Free Religious Association in the U.S., Abe and Uchigasaki began to get more interested in social reform than in church activities. The Japanese Unitarians came to think that their interest and energies for the liberal cause had been exhausted. Around the same time, MacCauley, now 76 years old, decided that it was time to retire. The A.U.A. sent John Day as his replacement in 1919. 　　The Japanese leaders hoped to be free of all foreign direction and wished entire charge of whatever money was given, so they were often opposed by Day. As a matter of fact, Day was surprised to find that MacCauley had allowed them freedom to organize church affairs. Day was a supporter of the conservative policy of the current A.U.A. leadership, which had by that time lost interest in Emerson’s idea of free religion. He did not want the Japanese branch of Unitarianism to get involved in any political or social issues. He also asserted that the Japanese branch should not expect any financial support from the A.U.A. if they did not want to follow his leadership. Day, particularly afraid that Yuaikai would become radical, told Suzuki to withdraw his society from Unity Hall. 　　In the end, Uchigasaki and Abe decided to renounce all financial help from the A.U.A. Moreover, the Yuaikai did not give up its use of the Hall. Discouraged by these negative attitudes, Day went back to the States in 1922. Soon after that, however, the Japanese Unitarians found that it was very difficult to support themselves without A.U.A. financial help. After the Great Kanto Earthquake of 1923, meetings stopped, and organized Unitarianism gradually went out of existence.  　　More than twenty years after the Mission withdrew from Japan in 1922, Imaoka resumed Unitarian fellowship. With some friends, he established Ki-itsu Kyokai (Association Church) in Tokyo in 1948, as a continuation of Ki-itsu Kyokai (the Association Concordia). At about the same time, he restarted the Japan Unitarian Association in cooperation with Rev. Akashi Shigetaro of Fukyu Fukuin Kyokai (General Evangelical Church) and others. Some months later, the J.U.A. was renamed Nihon Jiyu Shukyo Kyokai (the Japan Free Religious Association) to make it a more liberal religious organization. Its name was changed again to Nihon Jiyu Shukyo Renmei in 1952, though its English name remained the same. Imaoka acted as a link between the various groups working together in the Japan Free Religious Association and the Japanese members of the International Association for Religious Freedom. After Imaoka died in 1988, however, Ki-itsu Kyokai and the J.F.R.A. ceased functioning. At present, there are only a few people in Japan who keep Unitarian fellowship. 　　In retrospect, Japanese Unitarians were unable to balance the need to establish and maintain an organized group identity with the desire for freedom to pursue their individual ideals.