Soundwave on 06 November 2014
Yeah, surgery does that I guess. He's relatively luck though to be honest. He's required to take yearly medicals I believe as part of his position as president of Nintendo. If he wasn't, who knows may something like that could've gone unnoticed for years and become cancerous. So being president of Nintendo may have literally saved his life.
So at least there's that. Iwata has always looked younger than his actual age, now he's starting to look more his age. I'm sure he will regain weight as the months go on though.
