Kogasa is a cheery happy youkai, but gets easily depressed when things don't go her way (which is very often), typically when she fails to surprise someone despite her best efforts. She stated she wishes for vengeance on humans for being discarded. However, she's actually quite friendly to humans and her vengeance doesn't go beyond surprising and spooking humans. She gets genuinely pleased when she successfully surprises someone (or thinks she successfully surprised someone).
She despises not being taken seriously. She often attacks the protagonist in Undefined Fantastic Object in a fit of despair when she thinks they're making fun of her. She's displeased with children liking her eccentric design.
Kogasa suffers from self-esteem problems, as she is easily pushed into lamenting about wondering what her purpose is, or that she might be better off if she just went back to being an umbrella. Perhaps due to this, Kogasa is seeking a true purpose of existence for youkai, tsukumogami, and herself. She attempted this by starting a career in babysitting (which did not seem to go very well), surprising people (which also isn't going very well, though she's found some success in the Myouren Temple graveyard), and was even considering going back to being an umbrella just so she can be useful in that regard. She's stated that she's trying to imagine what humans want, and then plans on becoming that something they can use.[1] Deep down, it appears this pitiable illegally dumped object and troubled forgotten item just wants to be desired.
Her depression may also be another attempt at getting attention. She can get so depressed upon failing to surprise someone that it can become "a bother". In Undefined Fantastic Object, Reimu Hakurei wonders if Kogasa just wanted to be beaten up. That Kogasa ironically treats umbrellas like garbage by throwing them in certain spell cards leads Hatate Himekaidou to wonder if she wants to be treated like garbage, herself.
