I know I can look for a modern Japanese history book or read Wikipedia to learn information about Feudal Japan but what are the primary sources? I can look back at Greek and Roman history sources because I know about Tacitus and Xenophon and other Greek and Roman Works but who does a History Textbook reader go to to write about the Kamakura Period or The Sengoku Period or the others? Who wrote down the information?
The most comprehensive text about the Kamakura period is Azuma Kagami, the shogunate’s official history written around 1300, covering the time of the Genpei War and the early stage of the regime from 1180 to 1266.
Though not as reliable, gunki monogatari is the literary genre which illustrate the military history of feudal Japan in rather dramatic ways. Shinano no Zenji Yukinaga’s Heike Monogatari, the most notable work, covers the rise and fall of the Taira clan, and was melodized and narrated by biwa hōshi (lute priests). Conflicts prior to the Genpei War are also covered by gunki: Shōmon-ki on Taira no Masakado’s rebellion in 939, Mutsu Waki on the Zenkunen War from 1051 to 1062, Ōshū Gosannen-ki on the Gosannen War from 1083 to 1087, Hōgen Monogatari on the Hōgen rebellion in 1156, Heiji Monogatari on the Heiji rebellion in 1160, and Gikei-ki on the life of Minamoto no Yoshitsune (1159-1189).
However, more reliable sources favored by modern researchers are diaries written by noble families in Kyoto and records kept by religious institutions. Though they mainly focus on the authors’ occupational lives, they sometimes touch on unique information and views on contemporary events not found from samurai sources. Taira no Nobunori’s Heihan-ki (1132-1171), Nakayama Tadachika’s Sankaiki (1151-1194), Kujō Kanezane’s Gyokuyō (1164-1200) and Fujiwara no Teika’s Meigetsuki (1180-1235) are prime examples. The Hachiman Gudōkun of Iwashimizu Hachiman shrine, Konoe Motohira’s Jinshinin Kanpaku-ki (1255-1268) and Hirohashi Kanenaka’s Kanchū-ki (1274-1300) are known as great sources about the Mongol invasions in 1274 and 1281.
There are also a few books written in the feudal period on general history, such as Jien’s Gukanshō (c.1220) and Kitabatake Chikafusa’s Jinnō Shōtōki (1339), but they are rather used for studies of historiography than history itself.
For the Nanbokuchō period, the most comprehensive text is Taiheiki, a voluminous gunki which covers the time period from 1318 to 1368 from the Southern court’s point of view, as opposed to Baishōron (c.1349), which sides with the Northen court. Later conflicts are also covered by gunki: Meitokuki on the Meiroku rebellion in 1391, Ōeiki on the Ōei rebellion in 1399, Eikyōki on the Eikyō rebellion in 1438, Kakitsuki on the Kakitsu rebellion in 1441, Ōnin-ki on the Ōnin War from 1467 to 1477, and Kamakura Ōzōshi on Kantō conflicts from 1380 to 1479.
Notable diaries kept in the Muromachi period include Emperor Hanazono’s Hanazono Tennō Shinki (1310-1332), Tōin Kinkata’s Entairyaku (1311-1360), Nakahara no Moromori’s Moromori-ki (1339-1374), Madenokōji Tokifusa’s Kennaiki (1414-1455), Nakayama Sadachika’s Sakkaiki (1418-1443) and the Daigo-ji monk Mansai’s Mansai Jungō Nikki (1423-1435).
Sources from the Sengoku period are numerous. Some of the most popular gunki are Ōta Gyūichi’s Shinchōkō-ki on Oda Nobunaga, Obata Kagenori’s Kōyō Gunkan on the Takeda clan, Makishima Akitake’s Hokuetsu Gundan on the Uesugi clan and Oze Hoan’s Taikō-ki on Toyotmi Hideyoshi, though their reliability varies, and researchers rely more on original sources like letters and documents. Notable Sengoku diaries include Jinson and other monks’ Daijō-in Jisha Zōjiki (1450-1527), Yamashina Tokikuni’s Tokikunikyō-ki (1474-1502), Prince Fushimi Sadafusa’s Kanmon Nikki (1416-1448), Sanjōnishi Sanetaka’s Sanetakakō-ki (1474-1536), Yamashina Tokitsugu’s Tokitsugukyō-ki (1527-1576), and the Daigo-ji monk Gien’s Gien Jungō Nikki (1596-1626).
In 1779, the blind scholar Hanawa Hokiichi started to collect and compile important historical texts from throughout the nation, and published 1274 works in the 666 volumes of Gunsho Ruijū in 1819, which as well as its sequels are widely used by modern scholars.
Too many to list, if you are talking about Japanese writers who wrote our own history. Japan was very high on the literacy rate and papers were far more commonly available than the west at the time, and many samurai, nobles, monks and even merchants wrote diaries and chronicles. You've probably noticed that we have thousands of thousands of real historical figures just in the short Azuchi-Momoyama period during the Sengoku era, and that's because they were all documented by those everyday writers.
The first unified (academically edited) history book, Dainihonshi, was masterminded by Mitogaku scholars under Tokugawa Mitsukuni, a head of the Mito branch of the Shogunate family. The project had started in 1657 and the original set of books that covered the history until 14th century to the end of the Kamakura period was completed in 1715. But to complete to the end of the Edo period, it took until… 1906. In total, there are 266 books.
If you are talking about books in the western languages, people like Basil Hall Chamberlain, Lafcadio Hearn, Clement Ernest Wilson, Tenshin Okakura, and Francis Brinkley come to my mind.
For modern scholars, there's probably nothing as "definitive", for a lack of a better word, as Tacitus, Xenophon, Herodotus, etc, for an overarching history. The reason for this is we have so many sources. Sometimes they complement, and sometimes they conflict with each other. It's up to the scholar to pick out the relevant sources and analyse which ones are more trustworthy.
We have for instance:
For narrative history by people living at the time or soon after it (like Tacitus and Xenophon), we have various chronicles compiled throughout the period, ranging in style from more like a diary to more like a novel. For the (early) Kamakura Period we also have the official compiled history of the Shogunate, the Azuma Kagami.