I saw that he can't use his trait for kharmic but can he use it for invest?
"Once per turn, if Nishigori is unbowed, produce 3 Gold which can only pay for a single Strategy's action."
Yoritomo Nishigori + Invest
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.
I saw that he can't use his trait for kharmic but can he use it for invest?
"Once per turn, if Nishigori is unbowed, produce 3 Gold which can only pay for a single Strategy's action."
Yes - for a Strategy, the Invest cost is added to the cost of the action.
Similarly for Discipline.