You also stated in your letter that you have worshipped daily chanting the seven characters of the daimoku three times a day and have chanted, “Namu Ichijō Myōden” (Hail to the One-Vehicle Teaching of the Lotus Sutra!) 10,000 times but have discontinued these practices as well as recitation of the sūtra during menstruation. You would like to know whether it is permissible to refrain from these daily practices during menstruation or not, and how many days after menstruation you can go back to the daily practices.
This is the anguish of every woman, which many people have tried to answer in the past. However, nobody has worked out an answer, based on sutras probably because it isn’t clearly explained anywhere in the sutras preached by Śākyamuni Buddha during His lifetime. Having read almost all the Buddhist scriptures, I, Nichiren, have found clear references in them against drinking liquor, eating meat and five very spicy vegetables, or having sexual relations on specific days and months, but I can’t think of any sūtra or discourse showing dislike of menstruation.
Many young women became nuns while Śākyamuni Buddha was still alive, but they weren’t rejected during their menstrual cycle. For this reason, I believe that menstruation isn’t uncleanliness coming from outside but a physiological phenomenon peculiar to women and is indispensable for continuing the human race. It is like a long illness. For example, excrement and urine are expelled from our bodies, but they don’t do any harm to us as long as we keep our bodies clean. The same is true of menstruation; we have never heard that menstruation is especially taboo in India or China.
Japan, however, is a country of gods. It is due to this country’s customs that Japanese gods, who are manifestations of Buddhas and bodhisattvas, strangely do not conform with sūtras and discourses, in many cases. Therefore, if you disregard these customs, you will be punished externally. Closely checking sūtras and discourses, we come across a doctrine called Zuihōbini, or adapting precepts to a locality. The spirit of this admonition preaches that we should not go against manners and customs of the country unless it means a serious breach of Buddhist precepts. Those wise men who do not know about this, however, insist strongly: “Japanese gods are demons, whom we should not revere.” Thus, they have lost the trust of their members. From this, I, Nichiren, think Japanese gods probably dislike menstruation. Therefore, women born in this country should refrain from appearing before these gods during their period.
However, daily practice of Buddhism should not be obstructed by menstruation. Those, who insist that you skip daily services during menstruation, don’t really believe in the Lotus Sūtra. Their original intention is to break your true faith somehow; but since they can’t advise you directly to reject the Lotus Sūtra, they try to keep you away from it on the pretext of menstruation. They also try to threaten you into committing the sin of abandoning the true dharma by saying that practicing the Lotus Sūtra during menstruation means showing disrespect to it.
Keeping this in mind you should chant only the daimoku, without reciting the Lotus Sūtra, during menstruation even if it lasts for a week. Your daily services should not be in front of the sūtra. In case the end of your life is unexpectedly near, you may eat fish and poultry, and recite the Lotus Sūtra, if you can, and chant the daimoku. You don’t have to talk about your menstruation.
As for chanting “Namu Ichijō Myōden,” although it means the same, you should chant “Namu Myōhō Renge Kyō” as Bodhisattva Vasubandhu, Grand Master T’ien-t’ai and others did. There is a reason for me to say this.
Gassui Gasho, A Letter on Menstruation, Nyonin Gosho, Letters Addressed to Female Followers, Page 36-42