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 he is the only one in his army must I remove him? Can I choose not to activate the trait (due to the colon)?
Shikibu no Oni - exp Force/Chi:
8 / 4 Ho/Co/PH:
- / 9 / 0 Shadowlands. Nonhuman. Oni. Overlord. Experienced Oni no Shikibu. Unique. After Shikibu enters play: Lose 8 Honor. Before an action would destroy Shikibu: Negate his destruction. If he is in play after the action resolves, your target Personality at his location is consumed by Jigoku and removed from the game.
If he is the only one in his army must I remove him? Can I choose not to activate the trait (due to the colon)?
Yes, if Shikibu no Oni Exp is the only Personality at his own location when his trait triggers, you must remove him from the game.
No, the colon does not indicate that you have a choice in regards to a Triggered trait.
http://rules.l5r.com/Card_features?rulesl5_wiki_wiki_session=997fbdceb187cbbbf50db89d4ac904a2#Traits: "Traits that are triggered when paying a Gold cost, and whose effects produce Gold, do not have to be triggered when any given Gold cost is paid; they are optional. All other effects of triggered traits are not optional – they must happen if the trigger occurs."