“It’s just a normal umbrella monster.” – Reimu
One of the Gensokyo’s many features is the omnipresence of spirits. These spirits exist in virtually every aspect of this world, including the very tools its very residents use. One such tool was a defective umbrella that, after being discarded, morphed into a youkai. Angered and embittered by its abandonment, it swore to take its revenge upon humankind by filling their nights with fear. With its purpose now set, it gave itself a name: Kogasa Tatara.
The reality of the situation is, as per Touhou standards, a bit more benign than the term revenge would suggest. In practice, Kogasa carries out her ambushes with all the stealth and menace of a mother playing peekaboo with her child. She’s treated more like an annoyance than an actual threat and much of this has to do with the transition from the more violent Gensokyo of old to the current, post-isolation version. Back in the old days, humans had very real reasons to fear their youkai neighbors. Even a low-level, childlike youkai such as Rumia could trivially overpower, dismember, and devour the average human. Thus, Kogasa’s outlandish appearance wouldn’t have mattered since any and all supernatural creatures could be lethal. With the threat of arbitrary murder mostly gone, the umbrella youkai is only about as scary as a clown jumping out of your closet. Actually, that sounds pants-destroyingly terrifying, so perhaps a clown wasn’t the best comparison.
“In this day and age you can fly a little helicopter inside someone’s room. These days, nobody would be surprised by something like a flying umbrella.” – Sanae