Explosion said: Has it ever been said in the main games that the umbrella is her "main/real/primary" body?
I thought the relationship between those two was more like the situation with Youmu and her ghost-half.
Dunno about the games, but two points: 1. It's certainly her main body in yuzuna99 fanon - example: post #1086189. 2. A karakasa is a form of youkai that comes into existence when an umbrella has existed for 100 years and consequently becomes animate. Kogasa's umbrella (geta on the handle and all) is the traditional depiction of a karakasa - having a humanoid form at all is a Touhouism. If the umbrella isn't her main body, then ZUN is deviating from traditional legend, not that that's unheard of.
Regarding the umbrella as Kogasas real body, ZUN did mention in an interview regarding UFO that the umbrella is the real body and the humanoid form is an extra. http://www.youtube.com/watch?v=otIrJdoaITI
Symposium makes it clear that the two are inseparable, with the umbrella referred to as the main body using the word "hontai", which is what Byakuren uses here. Well, actually she uses it like a name, "Hontai-chan", which is very cute.
My, my, my.Kogasa, darling!Myyyyy!Miss Hijiri's puff puff greeting was so long that I'm all dizzy.This girl has always been out of it and hasn't kept in touch with me.Ooph!Here's a hug for your real-form, too!♡*Poffmph*I was really worried about you!!