This following is a very, very brief summary of the major existing schools of Buddhism in Japan, roughly in chronological order. There have been many entire books written on the subject, so this is intended primarily as a quick reference for myself; more information is (or someday will be) available behind the links.

When applicable (and available), for each school, person and theory I have given the romanization of the Japanese (linked), the kanji in Unicode, the Mandarin pinyin reading and an English gloss. Kanji are given in the modern Japanese simplified form (eg. 経 instead of 經 for kyou, "sutra"). I chose linking over phonetic accuracy, so the romanizations do not include long vowels -- those who care can reconstruct them from the kanji anyway.

As an exception, Sanskrit sutras have usually been linked under their English names, since e.g. Lotus Sutra is a bit more recognizable and a bit less of a mouthful than Saddharmapundarîka-sûtra.

Nara Period

Yogacara Schools 瑜伽行派

Hosso (法相, fa3xiang1, "Dharma Character")
Founder: Genjo (玄奘, xuan2zang4), China, c. 630 AD
First Introduction to Japan: Dosho, 654 AD
Major Influences: Sanron, Zen
Doctrine: yuishiki (唯識, "Consciousness Only")
Primary Text: Discourse on the Theory of Consciousness-Only (Jo yuishikiron 成唯識論)
Kegon (華厳, hua1yan2, "Flower Garland")
Founder: Dojun (杜順, du4shun4), China, c. 600 AD
First Introduction to Japan: Bodhisena, 736 AD
Major Influences: Hosso
Doctrine: shihoukai (四法界, "Four Realms of Reality")
Primary Text: Avatamsaka Sutra (Kegonkyo 華厳経)

Monastic Schools

Ritsu (律, lü4, "Vinaya")
Founder: Dosen (道宣, dao4xuan1), China, c. 650 AD
First Introduction to Japan: Ganjin (鑑真), 753 AD
Doctrine: Vinaya (the monastic rules in the Tripitaka)
Primary Text: Dharmaguptavinaya (Shibunritsu 四分律)

Heian Period

Esoteric Schools 密教

Tendai (天台, tian1tai2, named after founding temple)
Founder: Chigi (智?, zhi4yi), China, c. 550 AD
First Introduction to Japan: Saicho (最澄), 807 AD
Doctrine: sandai (三諦, "Triple Truth")
Primary Text: Lotus Sutra (Hokkekyo 法華経)
Shingon (真言, "True Word")
Founder: Kukai (空海), Japan, 816 AD
Major Influences: Tendai, Tantra
Doctrine: vajrayana/tantra (right-handed)
Primary Texts: Mahavairochana Sutra (Dainichikyo 大日経), Diamond Sutra (Kongokyo 金剛経)
Nichiren (日蓮, "Japanese Lotus")
Founder: Nichiren, 1253 AD
Major Influences: Tendai
Doctrine: Namu myoho renge kyo (南無妙法蓮華経)
Primary Text: Lotus Sutra (Hokkekyo 法華経)

Kamakura to Modern Period

Amidist Schools

Jodo (浄土, jing4tu3, "Pure Land")
Founder: Eon (慧遠, hui4yuan), China, c. 400 AD
First Introduction to Japan: Honen (法然), 1175 AD
Doctrine: nembutsu (念仏, "prayer to Buddha")
Primary Text: Infinite Life Sutra (Muryojukyo 無量壽経)
Jodo Shin (浄土真, "True Pure Land")
Founder: Shinran (親鸞), 1224 AD
Major Influences: Jodo
Doctrine: shintai zokutai (真諦俗諦, "Real Truth, Common Truth")
Primary Text: Infinite Life Sutra (Muryojukyo 無量壽経)

Zen Schools 禅宗

Note that Zen influences are identifiable earlier in Japanese Buddhism, esp. cross-fertilization with Hosso and Kegon, but the independent schools were formed quite late.

Soto (曹洞, cao2dung4, named after its founders)

Founders: Sosan (曹山, dung4shan1) and Tosan (洞山, cao2shan1), China, c. 850
First Introduction to Japan: Dogen (道玄), 1227 AD
Major Influences: Hosso, Kegon
Doctrine: zazen (座禅, "sitting meditation")
Primary Texts: Transcendental Wisdom Sutras aka Prajnaparamita Sutras (般若波羅蜜経), incl. Heart Sutra
Rinzai (臨済, lin2ji4, named after founder)
Founder: Rinzai, China, c. 850
First Introduction to Japan: Eisai (栄西), 1191 AD
Major Influences: Hosso, Kegon
Doctrine: koan (公案, "device; idea")
Primary Texts: Transcendental Wisdom Sutras aka Prajnaparamita Sutras (般若波羅蜜経), incl. Heart Sutra
Obaku (黄檗, huang2bo4, named after founder)
Founder: Obaku, China, c. 850
First Introduction to Japan: Ingen (隠元 ?), 1654 AD
Major Influences: Rinzai
Doctrine: kyozen itchi (経全一致, "Unity of Sutras and Zen")
Primary Texts: Transcendental Wisdom Sutras aka Prajnaparamita Sutras (般若波羅蜜経), incl. Heart Sutra

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