I'm afraid all I have right on me right now is this biographical sketch of Arii Shokyuu, because most of the rest of this sort of thing is in Japanese. Ema Saiko, though she didn't technically take Holy Orders, is another example of a woman of the same time period who cited devotion to religion and art as a reason not to take the typical roles. Earlier there was also Hojo Masako, a member of the family that ran the military junta during the Kamakura period, who is referred to as the 'Nun Shogun' (which is one of the more awesome sobriquets I've ever heard, I must say).

In a lot of these cases the women did have husbands and families at one point, but they died or left them or something else unfortunate befell them and the women didn't feel like killing themselves so this was the preferable option to solve the situation.

There is also Onibi (Demon Fire), a book by Yoshiya Nobuko--the author I'm going to be doing my thesis on--about Christian nuns in seventeenth-century Japan (hitherto these nuns I've been mentioning have all been Buddhist) that was originally pitched to me as The Power and the Floridly-Written, Ultra-Feminine Glory.