I feel Shirō Shimomoto is not convincing

For me, Shirō Shimomoto in GOKU-OH 2 (2019) is around 1/10. The role need more detail, but the performance stay on the surface. I do not hate it, but it did not pull me into the story. Many moments pass very fast and I do not remember much after it. For me it does not feel very real in many scene. I think the score is fair because I remember both good part and weak part.