Much of Nichiren Shōshū's underlying teachings are extensions of Tendai (天台, Chinese: Tiantai; Korean: Cheontae) thought.
Nichiren Shōshū doctrine extends Tendai's classification of the Buddhist sutras into five time periods and eight categories (五時八教: goji-hakkyō), its theory of 3,000 interpenetrating realms within a single life-moment (一念三千: Ichinen Sanzen), and its view of the Three Truths (三諦: Santai).