My husbando is Mihashi, on the left in pic related>Does he have any gap moe traits or hobbies?
I think gap moe means something that is cute, but unexpected for the character? In that case, I don't think he's "gap moe", just regular moe. He's the pitcher for his high school baseball team, but because of bullying in his previous school, he's very shy and nervous and has no confidence. His only hobby is baseball as far as I know.>What's his place in his source material, how does he effect the plot and the other characters?
He's the main character. He's kind of the baby of the team, so everybody has to look out for him and support him so that he can pitch well. It's very sweet seeing their relationships.>Does he have any close friends? If he does, what is their friendship like and how do they treat eachother?
The first character that comes to mind is the catcher, Abe (on the right in pic related). Abe is kind of rude and impatient, and he and Mihashi constantly misunderstand one another, but Mihashi respects him a lot and they work well together as a battery & try to work through their differences.