An ongoing topic of discussion among some folks concerns how to chant the Odaimoku. Is it Nam or Namu that precedes Myoho Renge Kyo? First, it is important to understand something about Namu as Namaste from which it derives. Namu is actually two characters in Chinese consisting of Na and Mu. This Namu is not a prefix to Myoho Renge Kyo, which is the full title to the Lotus Sutra. It is not merely an appending of one word, Namaste, to the other words of the title. Instead, it is a relational marker, which ties us, and our invocation of the title, to the contents of the Lotus Sutra. As such, it is important, regardless of how we say it, to be mindful of the implication of its use in the Odaimoku we recite. … [W]e open our self up in greeting, we empty our self in respect, and we fill our self up with devotion. I am not sure you will necessarily see this exactly the same way as I do, that is fair. I do think though that this is an important issue when one thinks about Namu.
Lecture on the Lotus Sutra