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.
A player, 7 October 2010
So, this just came up in a game:
If I have more personalities than my opponent who has at least 2, one of whom is Hisao and one of who is not, and I play Overwhelming Numbers, can my opponent choose Hisao (thus the card does nothing)?
Overwhelming Numbers Battle: If your current army has more units than the current enemy army: The enemy leader chooses and bows one of his unbowed Personalities in his current army.
Hisao Ronin • Samurai • Duelist • Hero Hisao will not gain Clan alignments. Negate the bowing of Hisao and his Followers from card's effects (not costs) while he is in an army.
A player, 7 October 2010
If I have more personalities than my opponent who has at least 2, one of whom is Hisao and one of who is not, and I play Overwhelming Numbers, can my opponent choose Hisao (thus the card does nothing)?
Yes he can choose Hisao whose trait will negate the bowing from your action, per Choices: "A choice may be made even if its consequences would be negated, prevented, or otherwise fail due to lack of suitable things to affect."