Let's say that I make Yaheiko a samurai through the card Gempukku. She becomes dishonored and my opponent plays remorseful seppuku. May I use her reaction to save her?
Hida Yaheiko and Remorseful Seppuku
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.
Seppuku is a rulebook effect, not a card effect. Also, hooray Lotus Rulebook!:
Personalities may be destroyed by a special effect called “committing seppuku”. This means “Restore the Personality to Honor. Destroy the Personality. These effects cannot be negated.”