Kageyama is actually very good in drawing.
And by very good, I mean seriously friggin' awesome.
Whenever they're having classes, he starts to doodle on pages of his notes be they blank or not because he isn't interested in the subject. Know the saying about laziness and boredom connected to intelligence? That, my friend, has just helped us to confirm that Tobio-chan is indeed a genius.
Whenever they pass homeworks or have seatworks involving drawing, he would end up turning in a pretty decent work, but he just can't draw as good as when he doodles absentmindedly because he thinks too much about the homework and doesn't get the chance to follow his natural sense for art.
There would be one time when Yachi will be trying to make a new poster for the volleyball club inside the gym a little while before they practice, and it just so happened that Kageyama gets into the place too early. He would find the manager there, trying to sketch something okay, so he approaches her. He borrows the pencil and draws a little something for a few seconds and when he moves away, Yachi is paralyzed.
The poster seriously turned out beautiful in the end and whenever they would compliment Yachi for her "work", she would be all anxious and would be sending glances towards Kageyama who doesn't even notice them.