YNET has an interesting story, or should I say video. Here is a snippet of text from YNET about the priest-turned-rabbi.
Rabbi Moshe Hatori is a learned scholar from Jerusalem who dedicates most of his time to studying Torah. Only few people know that the Japanese-born convert, who is an expert on the writings of the Vilna Gaon, used to be a priest and the head of a Christian congregating in Japan less than 20 years ago.
For many years, Hatori led a double life as a Christian pastor who observed Torah and mitzvot in secret. On Friday evenings, his wife would bake challot and he would say Kiddush, and on Saturday the couple would refrain from working. After havdalah on motzei Shabbat, Hatori would rush to prepare his church sermon for Sunday.