Men of the Two Vehicles such as Śāripūtra and Maudgalyāyana who had been the Buddha’s disciples awakened to their first aspiration for Buddhahood at that time of the Buddha’s first sermon at Deer Park. The Buddha, however, expounded only expedient teachings to them for more than forty years. Now in the Lotus Sūtra, He expounded the True Dharma. And when the eternity of the life of the Buddha was suggested in chapter 15 on the “Appearance of Bodhisattvas from Underground” in the essential section of the Lotus Sūtra, great Bodhisattvas, men of the Two Vehicles (srāvaka and pratyekabuddha), the King of the Brahma Heaven, Indra, sun god, moon god, Four Heavenly Kings, and Dragon King, who had listened to the Buddha preach ever since the preaching of the Flower Garland Sūtra, attained enlightenment, reaching the same rank as the Buddha or the one next to it. Therefore, when we look up to heaven today, we can see living Buddhas giving benefit to people while retaining their original ranks.

Hokke Shuyō Shō, Treatise on the Essence of the Lotus Sūtra, Writings of Nichiren Shōnin, Doctrine 2, Page 211