He was cast to play lead character Toru Watanabe in the film adaptation of Haruki Murakami's novel Norwegian Wood, which was released in December 2010.

His stage name uses the katakana spelling of his first name (ケンイチ) instead of the usual kanji (研一).

Matsuyama starred in Ultra Miracle Love Story in 2009, using the Tsugaru dialect of Japanese in the film.

He voiced the role of Balthazar Bratt in the Japanese dub of Despicable Me 3 in 2017.

[1] On April 1, 2011, he married Koyuki Katō, who co-starred with him in Kamui Gaiden.