The Aihara Clan (粟飯原氏)
The Aihara clan was a samurai family that played an active role during the Medieval Period.
The Aihara Clan of the Yokoyama Party
Some Aihara clan samurai belonged to the Yokoyama Party, one of the Musashi-shichito Parties (seven parties of samurai in Musashi Province.)
The clan name AIHARA "粟飯原" is also written as "藍原" in kanji (Chinese characters.)
They fought on the side of the Wada clan and died in the Battle of WADA in 1213. Their surviving descendants served the Tokuso Family (stem family) of the Hojo clan.
The Aihara Clan of the Chiba Clan
Some Aihara clan samurai belonged to the Chiba clan of Kanmu-Heishi (the Taira clan). At the beginning of Battle of Wada, Jiro AIHARA, a "hikan" (low-level bureaucrat) of "Chiba no suke" (Assistant Governor of Chiba Province,) apprehended Anenbo, who was carrying a treasonous circular letter, which triggered the revelation of the treason. Jiro AIHARA was a member of the Aihara clan, a branch of the Chiba clan of Kanmu-Heishi, and became a "hikan" of "Chiba no suke."
The Aihara Clan as Kyoto Bugyonin (Magistrate in Kyoto)
Kiyotane AIHARA, who seems to be a descendant of Rokuhara bugyonin (magistrate in Rokuhara,) worked as "Mandokoro Shitsuji" (chief of Mandokoro, the Administrative Board) and "hikitsukebugyo" (a magistrate for court of justice) in the Muromachi bakuhu (Japanese feudal government headed by a shogun.)
The relationship between him and the two Aihara clans above remains unclear.