Ikematsu who read the manga when he was 22 and claims to be a big fan, commented that he was very much affected by the manga and regarded Miyamoto Hiroshi as his hero as he respected how the character lived. As such, when he got the offer to play Miyamoto, he wondered if he was good enough to do so and pondered over it for about 2 months. As such, he would try his best to find the best way to play Miyamoto and treat this experience with the utmost respect. In addition, as Miyamoto shaved his head when he caused trouble with a rival company and needed to repent, Ikematsu had to do the same and laughed at himself for how he looked like Miyamoto in the manga. He also expressed admiration for Elephant Kashimashi even though he had never met them personally and revealed that he was thankful about them singing the theme song for his drama.
Sources: Natalie / Nikkansports / Oricon / Eiga.com