Within the Japanese Tendai tradition, the most fundamental branching is the historical division between the Sanmon and Jimon lines. The Sanmon-ha, often rendered as the “Mountain Gate” faction, is centered at Enryaku-ji on Mount Hiei and is regarded as the principal seat of the orthodox Tendai heritage. The Jimon-ha, or “Temple Gate” faction, is based at Onjō-ji (also known as Mii-dera) and arose in the context of succession disputes and institutional rivalry. These two currents are distinguished more by lineage, administration, and temple affiliation than by sharply divergent doctrine, yet they came to embody distinct emphases in practice and style of religious life. The Sanmon–Jimon polarity thus forms the primary axis along which Tendai’s internal diversity has been understood.

Alongside this main division, Tendai also developed various internal lineages and modes of practice that reflect its synthetic character. Esoteric practice, often referred to as Taimitsu, represents a Shingon-influenced current within Tendai that deepened the ritual and mystical dimensions already present from the time of Saichō and his successors. Other smaller lineages, such as those associated with particular temples like Rozanji, or named currents such as the Shinsei-ha, illustrate how specific communities within the broader school cultivated their own styles while remaining under the Tendai umbrella. These sub-branches do not so much break away as they articulate different facets of the same comprehensive vision.

In more recent configurations, the majority of these currents are gathered under the institutional framework of Tendai-shū, which encompasses most Tendai temples and lineages. Even groups influenced by Nichiren, such as certain Honmon Hokke-shū circles, sometimes trace their roots back to the Tendai milieu, underscoring how deeply Tendai’s synthesis has shaped later Japanese Buddhism. Across these branches and sub-branches, one can discern a single underlying aspiration: to hold together diverse practices—esoteric ritual, devotion, meditation, and scriptural study—within a unifying vision of the path to awakening.