Kotomi is a very fragile girl, both in body and in personality, so she is very easily scared. Because of this, she's also easy to capture due to her fear of bullies. While her eyes and hair often draw attention to her, she is also pretty healthy under her outfit and she does a good job of hiding it with her modest wardrobe. So long as the tie isn't too naughty, it's possible to get away with something that emphasizes her chest. Stick with cloth for her gag to help her calm down. The process is worth it as she has some of the cutest squirming in the area.