I feel Kentaro Nakajima is not convincing

For me, Kentaro Nakajima's work in Unification of Japan Gaiden: Yamazaki Ichimon 2 (2020) is easy to talk about after watching. Some emotions are too simple, and I cannot believe the character enough. Many moments pass very fast, and I do not remember much after them. For me, it does not feel very real in many scenes. I do not hate it, but it did not pull me into the story. This is only my personal view, but the performance changed how I enjoyed the film.