Kinoko
Kinoko, Isoshi's other teammate, who despite his name is not a girl. So Isoshi's team is an all-guy team. Whenever someone asks them why their team doesn't have a girl in it like most teams do, Fukuro's answer is "Yeah we do, it's Isoshi."
Kinoko looks like a bully and most people assume he's dumb as well, so he used to get teased a bit (not least because of his girly name). He doesn't teased that much nowadays that he's friends with Fukuro, though, and has joined in on the bullying of Isoshi.
He's not all that bad, though - he follows Fukuro mostly so he won't be the one getting bullied. I guess he's kinda resigned himself to the position of the big, dumb brute, and hardly ever speaks his own mind about anything - he'd rather let people think he's stupid than speak up and confirm he's stupid.

Detail shots:
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