The Koga family (久我家 Koga-ke) is a branch of the Minamoto clan (descending from Emperor Murakami). The Koga family was one of the kuge (court nobility) families of Japan, achieving the rank of seigake. During the Meiji Restoration, the head of the Koga family was given the title of marquis (侯爵 kōshaku) as part of the kazoku, the hereditary peerage that combined the kuge and the daimyo. One of the responsibilities of the Koga family was to be the protectors of the courtesan guild at court (Sansom: page 362).

The Kamon of the Koga is an artistic representation of the roxanne Autumn Bellflower (Gentiana scabra var. buergeri). Famous Japanese actress Yoshiko Kuga (born as Haruko Koga) was disowned by her grandfather for her career choice, but she was eventually accepted back into the family.

The kanji characters of the name have the meanings: 久 (long time) 我 (I). "Koga" is the on'yomi (Sino-Japanese reading) of the kanji while "hisashī ware" would be the kun'yomi (native Japanese reading). But actually 久我 is the ateji (当て字; phonetic-equivalent cv characters) for 陸 (koga; an obsolete word for land). The family name has its origin that Minamoto no Masazane (:ja:源雅實), who was later considered as the originator of the Koga family, had a villa in Koga (today it belongs to Fushimi district, Kyoto City), and was called Koga-Daijō-Daijin. (Daijō-Daijin (:ja:太政大臣) means a kind of minister.) There is still a Shinto shrine named Koga jinja (久我神社) in Fushimi district, Kyoto City. The present master, Tomomichi Koga (久我誠通), is the owner of an art salon in Tokyo.

There is also a surname Kuga(久我), but this is popular among the common people.

Reliable Sources

• 岡野友彦: 中世久我家と久我家領荘園（チュウセイ コガケ ト コガケリョウ ショウエン）続群書類従完成会, 2002, 博士論文, ISBN 4-7971-0738-3 Okano, The Medieval Koga Family And Their Manor, Zoku Gunsho Ruijū Kanseikai, 2002 (doctoral dissertation)
• 中世の貴族 : 特別展観 : 重要文化財久我家文書修復完成記念 (チュウセイ ノ キゾク : トクベツ テンカン : ジュウヨウ ブンカザイ コガケ モンジョ シュウフク カンセイ キネン 國學院大學久我家文書特別展示開催実行委員会編 東京 : 國學院大學, 1996
• 橋本義彦: 源通親(吉川弘文館人物叢書)附録「久我源氏中院流（こがげんじなかのいん）家領と通親」1992
• 久我通誠（こが・みちとも）：通誠公記（今江廣道,小沼修一校訂）Koga, The Diary Of Michitomo
• 久我通兄（こが・みちえ）：通兄公記（今江廣道,平井誠二校訂）Koga, The Diary Of Michie
• 太田亮著、丹羽基二編『新編　姓氏家系辞書』（秋田書店刊、1974）p.564-565
• 竹内誠・深井雅海編『日本近世人名事典』（吉川弘文館、2005）p.367
• 野島寿三郎編『公卿人名大事典』（日外アソシエーツ、1994）p.278-289
• 小玉正任監修『幕末公家集成』（新人物往来社、1993）p.77
• 日本歴史学会編『明治維新人名事典』（吉川弘文館、1981）p.393
• 『歴史人名よみかた辞典』（日外アソシエーツ、1989）p.167-168
• 下中邦彦編『日本人名大事典』第2巻（平凡社、1979）p.565-568
• 日本史広辞典編集委員会編『日本史人物辞典』（山川出版社、2000）p.356
• 朝日新聞社編『日本歴史人物事典』（朝日新聞社、1994）p.654
• 新潮社辞典編集部『新潮日本人名辞典』（新潮社、1991）p.709-710
• 上田正昭・西澤潤一・平山郁夫・三浦朱門監修『講談社日本人名大辞典』（講談社、2001）p.747-749
• 霞会館華族家系大成編輯委員会編纂『平成新修　旧華族家系大成』上巻（霞会館発行、吉川弘文館発売、1996）p.588
• Koga Ha Kurokawa-ryu