That's more interesting reading other's post than writing this one. X)
But just to be fair, here.
As I said a few times in the past in other threads, the first time I had that impression was with Rin. I live in the moment, I'm somewhat of an idiot, and I can be rough sometimes, but at the end of the day I'm unmistakably a good guy. Plus the problems finding a job. And the fact he grew up in a church is a similarity you just don't expect. We're not that different physically too, when I think about it. I'd have to check, but I think we're also almost the exact same height and weight. But, funnily enough, when I was a very young kid, I was actually a lot like Shiemi at that same age. Until I was 6, there was practically no kids my age where I lived. There was also no television. And the internet was barely even a thing at that time. Then I moved to some place where there were kids, and televisions, video games, manga, etc. Though I stayed the same for a while. Then, as I was on my way to become some silent teddybear like Mori from Ouran (though this manga didn't even exist yet), the other kids at the end of elementary school and the start of highschool couln't help but anoy the hell out of the silent guy, and as I started playing/fighting with them, I more or less slowly became very rowdy and arrogant, like most characters from Dragon Ball and Yu-Gi-Oh and One Piece, and eventually Mugen from Samurai Champloo too. Though, unlike these characters, I was also some sort of tsundere (even though that word wasn't even popular yet). Then I started martial arts, and I had to completly stop the arrogant act. It's easy to act arrogant when you're only fighting other kids who have no fighting skills just like you, but when you have practically none and you face someone who even has just a little more or worse if he has a lot more, you absolutly can't stay arrogant. So, for that time, I'm not sure who to compare myself with... Maybe Genos from One Punch Man? I had the "Please teach me Sensei/Senpai. You've got my full attention. I'll do everything you say." attitude, plus the discipline and hard work. But outside of training, I was just trying to live an easy life. I had no big mission and even less any vendetta like Genos has. Then, when I stopped my intense training in martial arts to become a translator, my easygoing side really took over. Wich may be compared to Yasaburou from Uchouten Kazoku. Actually, seeing this anime made me want to become even more easy-going, if that's even possible... And I shouldn't forget to mention Sword of the Stranger. I saw that movie a few years after it was released and some time after I gave up on martial arts as a profession, and it somehow helped me turn the page. When Kotarou asks Nanashi to teach him how to use a sword and he refuses, while I was wondering why he refused, I think I ended up feeling like him in realizeing that even though I'm glad I learned, I'm also glad I stopped, and even if Kotarou has a good point, I really wouldn't feel like teaching anyone.