What is a "Hiroshimakko"? The name "Hiroshima" from Mori Terumoto
The name "Hiroshima" is said to have been coined by the warlord Mori Terumoto. The nickname's roots lie in the delta of the Ota River.
"Hiroshimakko" is a word for someone born and raised in Hiroshima.
The key is how the name "Hiroshima" came to be — the naming story and the theories behind it.
What "Hiroshimakko" means
Hiroshimakkohiroshimakko
It means someone born and raised in Hiroshima, often spoken of with the city's castle-town history and a strong local attachment.
Source:国土交通省 太田川河川事務所「広島の地名の由来」
Mori Terumoto and the naming
Coining "Hiroshima"
The name is said to have been coined when Mori Terumoto built Hiroshima Castle at the mouth of the Ota River. It was not a major older place name, but one that spread with the castle.
Source:国土交通省 太田川河川事務所「広島の地名の由来」
Two theories (personal name / terrain)
Personal-name and terrain theories
One theory joins the "Hiro" of Oe no Hiromoto, an ancestor of the Mori, with the "shima" of the local lord Fukushima Motonaga. Another says the castle sat on a "broad island" (hiro-shima) in the delta. Neither is settled; accounts vary.
Source:広島県 公式サイト「県のプロフィール」
A city on the delta
The delta
Central Hiroshima sits on a delta built by the Ota River. Behind the character for "island" lies this watery, deltaic terrain.
Source:広島県 公式サイト「県のプロフィール」
FAQ
Do people use "Hiroshimakko" about themselves?
Yes. With a strong local attachment, people raised in Hiroshima use it fondly of themselves.
What is the "island" in "Hiroshima"?
Accounts vary. The terrain theory ties it to a "broad island" in the delta; the personal-name theory takes the "shima" from the local lord Fukushima Motonaga.