Hmm, I got a different vibe from his character. To me, Yamato seems to be going through a life-long crisis of identity and that his entire life is in itself a journey to discover who exactly he is and what it is that he wants in life. It just so happens that he is very good at fighting, but whether that is something he truly enjoys is a different matter. But I do have to admit that some of the things that are introduced could be fleshed out more, and that just leaving them makes his character seem a bit erratic and odd.