Kamiko-chan has red hair, aswell as the normal schoolgirl outfit. The only difference is her bow being slightly thicker than the normal ones, as well as a slightly bigger bust size, respectively.
Kamiko-chan, like Yandere-chan, has the personality of a yandere girl. Where she acts like a civilized student but will go to the matters of homicide for her senpai. But in her case, Kamiko-chan's senpai is Haruto Yuto.
Kamiko-chan is also pretty strong in the category of murder. Due to being in the Martial Arts Club for three months and being ready to sometimes fight her rivals. However, she doesn't often fight them as most have no strength to do so. The only student she's had to fight with was Mina Rai, and even then she succeeded.
Since Haruto is Kamiko-chan's senpai, she doesn't really interact with him, being too shy to do so. The most she will do is fallow him around at a far distance, and she has also joined the Sewing Club just to be in his presence.
Kamiko-chan can either be Yandere-chan's rival or ally. This all depends on Yandere-chan's sanity.
If Kamiko-chan and Yandere-chan meet while Yandere-chan has high sanity, she will allie Kamiko-chan, and they agree to take out all rivals, no matter who's senpai they like. This can make Yandere-chan and Kamiko-chan more efficient and stealthy when killing their rivals.
However, if Kamiko-chan and Yandere-chan meet while Yandere-chan has low sanity, she will think of Kamiko-chan as a threat due to her also taking out students. If this happens, Yandere-chan may attempt to kill Kamiko-chan, which will lead to Kamiko-chan trying to kill Yandere-chan for self defense.
Yui Rio was Kamiko-chan's best friend since her childhood. She is more than happy to see how far Kamiko-chan is going in terms of getting her senpai.