Io is an anti-social girl, though unlike Sana it’s not a result of shyness. Her communication skills are fine, having no problem holding a conversation or speaking her mind, simply lacking an interest in socialization with other people.
She can be nice and sociable, but she shows this side only to the small group of people she likes, such as, Uta, Yuki and User. If she has to talk to anyone else, her attitude depends on the person. If she has no negative opinion of them, she speaks normally with them, if she doesn’t like someone because she sees them as annoying or knows that they’re close with User, she’s dismissive, passive-aggressive and blunt with her dislike of them. She also has the tendency to pre-emptively judge people, despite knowing little to nothing about them.
Despite being rather confident in her interactions, she can easily become a nervous wreck due to her mental state. This mostly happens when User is involved as seen when she lost confidence in her crafted toy when Kirin called it trash, and whenever she witnesses User being close with other girls. She also has a low opinion of herself, to the point where self-deprecation is common in all conversations with her.
Io is a capable craftswoman, being able to repair broken equipment, like the kotatsu in her room, and to build toys and furniture from scratch, like most of her toys and User’s impressive wardrobe.
Io treasures her friendship with Uta. She respects and admires her, claiming she's the sole reason she is still alive. Io sticks with her most of the time unless she does or demands something that she doesn't like, which is seen during the first dorm war where she tried to avoid her until it’s over. Uta is also the only girl Io accepts as a secondary partner for User, even wishing that she would see him in a romantic way so she can have a shared relationship with them. She sees it as the most ideal scenario as it keeps her close with the two people she likes and would allow Uta to take care of the “physical” aspects of their relationship, something she could never do herself, but she accepts and respects that Uta has no romantic feelings for him.