For an indepth discussion on the way the Daimoku is spoken today and in Nichiren's day please see topic: "What do you wish me to discuss or correct?"

We are lucky enough to have a Japanese linguist arguing for the correctness of Nam Myoho renge kyo and myself arguing for Namu Myoho renger kyo.

https://markrogow.blogspot.com/2021/06/what-do-you-wish-me-to-discuss-or.html?showComment=1623910174255#c4287351546906017640