Speaking of attainment of Buddhahood by this female dragon, therefore, Grand Master Miao-lê writes, “The great blessing despite little practice shows the power of the Lotus Sūtra.” As this female dragon is indebted to the Lotus Sūtra for attaining Buddhahood, how could she abandon practicers of the sūtra even without the Buddha’s command? So, she says in verse praising the Buddha,”I will widely disseminate Mahāyāna Buddhism to save the suffering people.” This vow of the female dragon is at the same time the vow of all the dragons who follow her, which is so deep that the mouth cannot express it and the mind cannot fathom it. The Sāgara Dragon King, father of the female dragon, was a beast in body but had a deep compassion for his children that he gave the greatest treasure in the ocean, a wish-fulfilling gem, to his daughter as a donation upon her attainment of Buddhahood with the present body. This gem was worth as much as all things in the whole world.
Kitō Shō, Treatise on Prayers, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 63-64