According to Nichiren, all Buddhas are subordinates to Shakyamuni Buddha

"Thus it was revealed that Sakyamuni had long been the Buddha since the eternal past, and it became clear that various Buddhas in other worlds were all manifestations of Sakyamuni Buddha. In the pre-Lotus sutras, as well as the theological section of the Lotus Sutra, various Buddhas and Sakyamuni Buddha were on the same level, each practiced Buddhism on their own. Therefore, those who considered various Buddhas to be their main figures of worship did not worship Sakyamuni. Now, however, as Sakyamuni was proved to be the Eternal Buddha, those Buddhas on the lotus petals in the Flower Garland Sutra, or Buddhas in the Hodo, Hannya, or Great Sun Buddha sutras all became subordinates of Sakyamuni Buddha." -- Opening of the Eyes