In 2012, Keiichi was cast as Sakamoto, a chief officer in The Railway Man (2013). He acted beside Jeremy Irvine. He then played a ninja in The Wolverine (2013) alongside Hugh Jackman. In 2013, he was cast as Omori Guard in Unbroken (2014), and worked under the direction of Angelina Jolie.

In 2017, he was featured as main cast in The 48 Hour Destination (2017), a TV series episode.

He then worked on several feature films, including Dora and the Lost City of Gold (2019) with Isabela Merced, Love and Monsters (2020) with Dylan O'Brien, Loveland (2021) with Hugo Weaving, Godzilla vs. Kong (2021) with Millie Bobby Brown, and Young Rock (2021) with Joseph Lee Anderson.