it can be confusing sometimes because many female and male names end in 'o' but I think it's mostly female names which start with 'Mi'
As Mike-san pointed out, there are so many common male given names that start with "Mi", e.g., Mikio, Mikinori, Mikihiko, Mikihisa, Mikiya, Michio, Michishige, Michitada, Michitarō, Michinobu, Michinori, Michimasa, Michiya, Michiru, Mitsuo, Mitsukuni, Mitsuhiko, Mitsuyoshi, Mitsuru, Minato, Mineo, Mineya, Minoru,,,.