Mikihiko was initially described as a slender, nervous-looking boy during his short appearance in the first volume on the enrollment day when he left the classroom first, skipping guidance and proceeding straight to registration unlike his other classmates.
In a scene in the first chapter of Volume 3 that serves as his formal introduction into the series, despite being slender, he was depicted as someone who can be more accurately called well-built.
Mikihiko is extreme in his aloofness and not once was he seen conversing with anyone in their class, making him look anti-social. It was revealed later that he was simply a shy person. He also takes an interest in Shibata Mizuki's unique 'eyes', which later develops into romantic feelings for Mizuki herself, as it is hinted in the novels.