Koga (surname)

Koga (古賀, 甲賀, 弘化) is a Japanese surname.

Origin and Meaning

The surname Koga has multiple possible origins and meanings, depending on the kanji used to write it.

• 古賀: This is one of the most common forms. "古" (ko) means "old" or "ancient," and "賀" (ga) signifies "congratulations" or "celebration." A possible interpretation could relate to an old or established family with a history of prosperity.

• 甲賀: This form references the Kōga region in Shiga Prefecture, historically known for the Kōga ninja clan. "甲" (kō) can mean "armor," "shell," or "first (in rank)," and "賀" (ga) means "congratulations" or "celebration." This surname likely indicates an ancestral connection to the Kōga region or the Kōga ninja.

• 弘化: This is a less common form. 弘化 was also the name of a Japanese era (nengo) from 1844-1848. "弘" (kō) means "vast" or "broad," and "化" (ka) means "change," "convert," or "influence." This version is less likely to be a direct geographical reference and may have a more symbolic or historical significance.

Distribution

The surname Koga is found throughout Japan, but is more prevalent in western Japan, particularly in Kyushu and the Kansai region, near the historical Kōga area.

Notable People

Notable individuals with the surname Koga include:

• Koga Sadaichi (古賀 定吉): A prominent figure in the Meiji Restoration.
• Koga Issaku (古賀 逸策): A Japanese engineer.
• Koga Toshihiko (古賀 稔彦): A Japanese judoka and Olympic gold medalist.

Cultural Significance

The surname Koga, particularly when written as 甲賀, carries a strong association with the Kōga ninja clan, a significant element in Japanese popular culture and history. The other forms of the name, while less directly linked to ninja lore, still represent a common and respected Japanese family name with diverse possible origins.