Succession in the Hyoho Niten Ichi-ryū (the name given by Musashi towards the end of his life) does not follow a hereditary pattern.
The Gosho-ha Hyōhō Niten Ichi-ryū disputed the lineage claiming that Iwami Toshio Gensho is the sole legal representative of Hyōhō Niten Ichi-ryū until 2007.