I like the character of Isamu.
While he's perhaps not the most unique(Please don't take this as an insult, it's not meant to be and I would argue many of my characters are not at all unique) He is I think what this board lacked for a very long time. There are not very many NFU here, at least not hugely recognizable ones. Off the top of my head I can really only think of three or four, and all of them are singularly based around companies save for one. I think Isamu as a character is very well done, and he fills a roll that I think we've needed for a long time, one that I've always wanted to write...but just never got around to.
Kudos to you, as for actual feedback on what you could do better in my eyes;
I think one of the biggest aspects thats always kind of bothered me is that Isamu reminds me a whole hell of a lot of...well his playby. Maybe it's because I tend to associate characters to their avatars(This is part of why i dont utilize actors or irl people) but the association has always been very strong for me. Personally, I'd enjoy seeing Isamu kind of drift away from...Stannis like behavior and develop a bit more differently as a character.