After graduating from high school Mitsushima moved to Tokyo from Okinawa, he worked as an after-school childcare worker there,[4][5] and became a production director for the film Be Sure to Share.

After living in Tokyo for about two years, he took a chance to cycle around Japan for seven months from May to November 2009.

[6] In 2010, he made his acting debut as the lover of Tomoko Nakajima's character in Osorubeki Oya-tachi performed in the Tokyo Metropolitan Theatre.

[6][7] Mitsushima made his starring debut in the film Zoku Ittara Jinsei Kawatta www released 9 November 2013.

In 2019 Mitsushima announced on his official Instagram his agency has changed to from Humanite to Veleta 104.