Tanaka's Taking Over As CEO...

Everything was well-planned out. Tanaga was to spend some time with Tanaka, so he'd be informed of the things he needed to know as the CEO of THJ Group, and butler Ruffy would also return to Japan to accompany and assist Tanaka. 

Tanaga spoke with Koji to inform him of his plans about guiding Tanaka and assist him in running the company. Koji was more ecstatic when hearing Tanaka was returning to Japan, and Tanaga wasn't. He had plans of his own, and the fact that Tanaga was now out of the picture helped it greatly. 

As a precaution to make sure no one suspected him, Tanaka would live in Tanaga's mansion and act as if he was Tanaga himself. This plan would continue until Tanaga was finally finished with his treatment, so, for now, Tanaka would have to live as Tanaga.