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.
If I play Brash Hero:
Text Open: If it is not your turn: Target one of the active player’s Samurai Personalities with a Chi of 2 or less. The target’s controller must assign him during any Attack Phases this turn if he can legally do so.
On a legal target. Does my opponent have to attack me on his turn?
If I play Brash Hero on a legal target. Does my opponent have to attack me on his turn?
No.