Tachikawa-ryū
The Tachikawa-ryū (立川流) was a branch of Shingon Buddhism founded in the early 12th century by Ninkan (仁寛, died 1114), a monk of the Daigo-ji lineage of Shingon who was exiled in 1113 to the province of Izu (part of modern Shizuoka Prefecture) after being implicated in a plot to assassinate the then reigning emperor of Japan, Emperor Toba. During the late medieval period, the Tachikawa-ryū became notorious after monks of other Shingon lineages accused it of practicing heterodox rites involving sexual intercourse and skull worship, which contributed to its decline and subsequent dissolution during the Edo period.