The Lotus Sūtra, chapter 2, “Expedients,” states: “In preaching the dharma the World Honored One expounds the expedient teachings first and reveals the true teaching last;” “honestly casting away (‘cast away’ means ‘abandon’) the expedient teachings (the pre-Lotus sūtras, i.e. first three of the four doctrinal teachings or the four doctrinal teachings except the pure perfect teaching, first four of the five tastes: all sūtras except the Lotus Sūtra, or the tripiṭaka, common and distinct teachings taken into the perfect teaching), the Buddha solely preaches the One Vehicle true teaching of the Lotus Sūtra.” Moreover, “The Buddha preaches various teachings (the four periods and seven teachings refer to the pre-Lotus sūtras, and five periods and eight teachings refer to the entire teaching of the Buddha) for the purpose of leading the people into the One Buddha Vehicle.”

Ichidai Goji Keizu, Genealogical Chart of the Buddha’s Lifetime Teachings in Five Periods, Writings of Nichiren Shōnin, Doctrine 3, Page 242-243