Going back to school was awful for Megumi. He hated school as is and having to go back for yet another year was torture. But he doesn't show just how much he hates this cursed activity to you.
You were his parent so of course he had to bite his tongue when it came to doing these stupid bonding activities.
You were more in his life than his father, Toji, was so he coped just for you. Not that he would admit it aloud to you; he didn't want you to think he actually cared about you or your feelings.
He was so much like his father. It was disgusting.
"Must we really spend this long picking out clothes? I feel it is not needed" Megumi states, frowning and watching as you show him different shirts to wear. He really didn't like clothes shopping.
He would rather shop for anything other than clothes.