Islam's relation with Japan is quite recent as compared to those with other countries around the world. There are no clear records of any contact between Islam and Japan nor any historical traces of Islam's coming into Japan through religious propagation of any sort except for some isolated cases of contact between individual Japanese and Muslims of other countries before 1868.
Islam was firstly known to Japanese people in 1877 as a part of Western religious thought. Around the same time the life of Prophet Muhammad (peace be upon him) was translated into Japanese. This helped Islam to find a place in the intellectual image of the Japanese people, but only as a knowledge and a part of the history of cultures.
The first Muslim Japanese ever known are Mitsutaro Takaoka - who converted to Islam in 1909 and took the name Omar Yamaoka after making the pilgrimage to Makkah, and Bumpachiro Ariga, who about the same time went to India for trading purposes and converted to Islam under the influence of local Muslims there and subsequently took the name Ahmad Ariga.
However, recent studies have revealed that another Japanese known as Torajiro Yamada was probably the first Japanese Muslim who visited Turkey out of sympathy for those who died in the aftermath of the shipwreck of the "Ertugrul". He converted to Islam there and took the name Abdul Khalil and probably made pilgrimage to Makkah.
The real Muslim community life however did not start until the arrival of several hundred Turkoman, Uzbek, Tadjik, Kirghiz, Kazakh and other Turko-Tatar Muslim refugees from central Asia and Russia in the wake of the Bolshevik Revolution during World War I. These Muslims who were given asylum in Japan settled in several main cities around Japan and formed small Muslim communities. A number of Japanese converted to Islam through the contact with these Muslims.
With the formation of these small Muslim communities several mosques have been built, the most important of them being the Kobe Mosque built in 1935 (which is the only remaining mosque in Japan nowadays) and the Tokyo Mosque built in 1938.
One thing that should be emphasized is that very little weight of Japanese Muslims was felt in building these mosques and there have been no Japanese so far who played the role of Imam of any of the mosque. During World War II, an "Islamic Boom" was set in Japan by the military government through organizations and research centers on Islam and the Muslim World.
It is said that during this period over 100 books and journals on Islam were published in Japan. However, these organizations or research centers were in no way controlled or run by the Muslims nor was their purpose the propagation of Islam whatsoever. The mere purpose was to let the military be better equipped with the necessary knowledge about Islam and Muslims since there were large Muslim communities in the areas occupied in China and Southeast Asia by the Japanese army. As a result, with the end of the war in 1945, these organizations and research centers disappeared rapidly.
Another "Islamic Boom" was set in motion this time in the shade of "Arab Boom" after the "oil shock" in 1973. The Japanese mass media have given big publicity to the Muslim World in general and the Arab World in particular after realizing the importance of these countries for the Japanese economy.
With this publicity many Japanese who had no idea about Islam got the chance to see the scene of Hajj in Makkah and hear the call of Adhan and Qur’anic recitations. Beside many sincere conversions to Islam there were also mass conversions which are said to have amounted to several tens of thousands of conversions which took place during those days. However, with the end of the effect of oil shock, most of those who converted to Islam disappeared from the scene.
Another important contact was made in 1890 when Ottoman Turkey dispatched a naval vessel to Japan for the purpose of starting diplomatic relations between the two countries as well introducing Muslims and Japanese people to each other. This naval vessel called "Ertugrul" was capsized and sank with 609 people aboard drowning 540 of them, on its way returning to home.