The clan claimed descent from the Seiwa-Genji. The clan was founded by Ashikaga Kōshin (died 1330) who the son of Ashikaga Yasuuji (1216-1270). Near the end of the 13th century, the Isshiki were established as head of Isshiki Domain in Mikawa Province; and the name dates from this time.
The family lost its domains during the wars of the Sengoku period.
- Papinot, Jacques Edmond Joseph. (1906). Dictionnaire d’histoire et de géographie du Japon; Papinot, (2003). "Isshiki," Nobiliare du Japon, p. 16; retrieved 2013-5-25.
- Sesko, Markus. Legends and Stories Around the Japanese Sword, p. 64.
- De Benneville, James Seguin. (1916). Tales of the Samurai: Oguri Hangwan Ichidaik, p. 136 note.
- Rowley, Gene. (2013). An Imperial Concubine's Tale, p. 27.
- Ōta, Gyūichi. (2011). The Chronicle of Lord Nobunaga, p. 140.