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.
Battle: Choose your performing defending Courtier: Bow a target enemy Personality. After the next time this turn another player's action or a battle resolution destroys your Courtier, draw a card and choose a player, who gains or loses 2 Honor.
if i play this card on my opponent's personality and when my courtier dies i choose him to lose honor, can he use seppuku on the personality that i chose previously?
Yes he can, assuming the targeted Personality is a Courtier or a Samurai. That player ability triggers "before you lose Honor from an action that targeted or was performed by one of your Courtier or Samurai Personalities". If you choose the Honor loss, it comes from an action (The Shadow Court), so it is a valid trigger.