beta
He has a muscular body, and judging from the fact that he is a judo wrestler, it's normal for him to be chubby.
But, the story is based off Korea.. he'll definitely be considered fat
PLUS! they're also basing it off models, so if we're comparing him to models then you'll see why he thinks he's fat.
Overall tho, I think he's just big compared to the people there - he has also mentioned that he's been like that since he was a child.