It originated from around the13th century, the first son of Yoshiuji ASHIKAGA (the third family head of the Ashikaga family), Osauji established his home base in Kiranosho, Aomi County, Mikawa Province (present Nishio City and Hazu County, Aichi Prefecture), then commenced calling himself, 'Kira.'
13世紀の頃、足利義氏(足利家3代目当主)の長男・長氏が三河国碧海郡吉良荘（現・愛知県西尾市・幡豆郡）を本拠としたのを契機に、「吉良」を名乗りとしたことに始まる。