What are the chances that those creepy things are summoned by Kagari hersel so she can play the protector? They became worse the day after Ageha told Kagari she was scary. The kissing is probably not required either.
Probably not directly summoned? With this type of thing, the act of engaging with Kagari would make her more aligned with spirits. Also spirits may be drawn to Kagari herself.
I'm sure Kagari lets things progress further than necessary. She always gets there exactly when Ageha can't deal with the situation by herself, which wouldn't be possible if you weren't close by. I also get the sense she likes other people judging Ageha and isolating her since it lets her be the kindest person in Ageha's life.
I guess we'll never know her full motivations though. The pain of the one shot.