Io Naruko

Ichiban is in the same grade as Naruko. He considers Io to be his rival, due to the fact that Io has managed to defeat his winning record of achieving #1 all through his life on school tests. He was displeased with how his classmates praised Naruko over having money and for being sociable, despite him (Ichiban) placing first at school and not having any of the attention for it, unlike Io who despite placing second, was getting all the attention.

Shou Komi

Ichiban is in the same grade as Shou.
Shou and Ichiban binan
They were both turned into monsters by the Conquest Club and healed by the Defense Club.

Later in episode 11 the two are shown talking to each other, appearing friendly as they do so. It is likely they have become good friends since they were healed.