There is an anime character called Shimotsuki Shun from Tsukiuta. He is a mysterious, easy-going and laid back young man who leads the idol unit Preocellarum.
Shun Ishikawa is a Japanese professional baseball infielder for the Chunichi Dragons in Japan's Nippon Professional Baseball. Along with teammates Takuya Kinoshita and Shota Tomonaga, he was selected for the Western League representative team for the 2016 Fresh All-Stars game in Okayama. Ishikawa started the game at first base, batting 6th and managed one hit in his 3 at-bats.
Based on some research that I've done (gathering names from passenger lists and US census data), Shun was a pretty uncommon name for girls to have in the late Edo period and the Meiji period.2 syllable names were preferred at the time, more so before the Meiji period, which is why Shun was seen as a girl's name. Towards the 2nd half of the Meiji period and the Taishō period, those types of names were quickly shunted out in popularity by names ending in *ko.