my personality with 3 chi has a dotanuki challenges a personality with 3 chi. can my opponent use hidden strength?
dotanuki + hidden strength
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.
my personality with 3 chi has a dotanuki challenges a personality with 3 chi. can my opponent use hidden strength?
Dotanuki gives its Chi bonus while the Personalities are in the duel, so when Hidden Strength compares the Personalities' duel stats after the duel starts, the +2Chi from Dotanuki will already be applied.
In the scenario you describe, the delayed effects of Hidden Strength will be triggered.