Kabocha is a Japanese word for pumpkin or squash, and this particular dark green one is the major pumpkin that Japanese people farmed till other types of squashes were imported.
I don’t remember seeing any other colors or shapes of pumpkins 30 years ago in Japan.
It’s widely known in Japan as Hokkaido’s (the north island of Japan) famous produce, approximately 50% of Kabocha is from Hokkaido, many people believe that Kabocha is originated from Japan.
However, pumpkins are originated in central and south America, as you know. The first pumpkin was brought to Japan in medieval times by Portuguese traders.
Europeans used to use the south rout to come to Japan, so ships passed south Asia often stopped by southeast Asian countries before arriving in Japan.
Japanese saw the pumpkins and heard Portuguese traders were saying “Cambodia”. It sounded like “Ka-bo-cha” to people. The Japanese thought that pumpkin was Kabocha.
So, the actual meaning of Kabocha is….. Cambodia!