Oizumi first made a name for himself in a Hokkaidō-based TV variety series called "Suiyō Dōdeshō" (How do you like Wednesday?) and has been actively appearing on various media programs in Hokkaidō since then. He is also a member of a 5-piece drama group called TEAM-NACS formed when they were at Hokkai Gakuen university. TEAM-NACS had run their first national tour with thieir 11th original play called "COMPOSER" during spring and summer in 2005, and are now preparing for the 12th one called "HONOR" performances in Tokyo, Osaka and Sapporo; opening at The Galaxy Theatre in Tokyo on March 9, 2007 and closing at Doushin Hall at Sapporo on May 13, 2007. In 2007, he provided the voice of Professor Hershel Layton in the puzzle video game Professor Layton and the Curious Village as well as its sequels and movie.
Along with increasing popularity of "Suiyo Doudeshō" ("How do you like Wednesday?") and TEAM-NACS not only within Hokkaidō but throughout Japan over the past years, he has been expanding his works in various fields by appearing on nationwide TV dramas and films, doing character voices on animated films and releasing CDs as a singer. In addition to voices, he is also an accomplished writer and painter. He calls his fans "Koneko chan tachi", which means "kittens" in Japanese, although he does not like cats.
On May 30, 2011, he became the father of a baby girl. On his website he jokes saying, "Today I successfully became a father!"