can she cast it all by her self?
Soshi Yorimi with Illusory Defense
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
can she cast it all by her self?
Not unless she has effects on her that provide enough of a bonus to her Chi to get her to 10+ Chi.
Yorimi cannot use her trait to negate her bowing for the cost of Illusory Defense and "bow" three times. Even if she could, she would still only provide 4 of the required 10+ Chi.