Mito Kohmon’s real name was Tokugawa Mitsukuni (July 11, 1628 - January 14, 1701). He was a famous territory lord during the Edo era, and many TV dramas have been made using the “Mito Kohmon” name. As a result, almost all Japanese know about him.
I went on a trip to Ibaraki prefecture and saw his villa last Sunday. He lived there after he retired, and eventually wrote a history book. The villa has a large, beautiful garden and receives many visitors each year.
When I was a kid, children were always joking about Kohmon because the word has the same pronunciation as “school gate” and “anus”. Kids must still make this corny joke even now.