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, 24 October 2011
Situation is this, Player A attacks and Player B assigns no units to defend and only has one personality Shosuro Aroru in his home. Player A players hunting the daughter, targeting Shosuro Aroru. Can Player B react with Shosuro Aroru, targeting a holding or Stronghold and as a result move home after the resolution of hunting the daughter?
Secondly if Player B had assigned Shosuro Aroru to a different provence than the attacker and was dragged over, would it be legal to take Shosuro's reaction?
Hunting the Daughter Battle: Choose your performing unbowed Scout, and bow him unless the current battlefield's province was targeted by a Recon action this turn: Move another player's target Personality to this battlefield. Straighten him. If you are a Crab Clan player, you may take an additional Battle action.
Shosuro Aroru (Experienced 2) Scorpion Clan • Ninja • Duelist • Experienced 2 • Unique Will not attach non-Ninja Followers. Reaction: When an action would target a Ninja at Aroru's location: Choose another of your cards. The action targets it instead, if legal. After the action's resolution, you may move Aroru to a different location. Battle: Other players may not take Reactions until this action ends. Ranged 5 Attack.
Brook Cunningham (rules official), 24 October 2011
Situation is this, Player A attacks and Player B assigns no units to defend and only has one personality Shosuro Aroru in his home. Player A players hunting the daughter, targeting Shosuro Aroru. Can Player B react with Shosuro Aroru, targeting a holding or Stronghold and as a result move home after the resolution of hunting the daughter?
Secondly if Player B had assigned Shosuro Aroru to a different provence than the attacker and was dragged over, would it be legal to take Shosuro's reaction?
Hunting the Daughter Battle: Choose your performing unbowed Scout, and bow him unless the current battlefield's province was targeted by a Recon action this turn: Move another player's target Personality to this battlefield. Straighten him. If you are a Crab Clan player, you may take an additional Battle action.
Shosuro Aroru (Experienced 2) Scorpion Clan • Ninja • Duelist • Experienced 2 • Unique Will not attach non-Ninja Followers. Reaction: When an action would target a Ninja at Aroru's location: Choose another of your cards. The action targets it instead, if legal. After the action's resolution, you may move Aroru to a different location. Battle: Other players may not take Reactions until this action ends. Ranged 5 Attack.
Yes, in both those scenarios, it would be legal to take Aroru's Reaction.
"Choose another of your cards" is not restricted in any way, so you could pick your Stronghold or a Holding. The effect "The action targets it instead, if legal." would fail, because such a card is NOT a legal target for Hunting the Daughter. Then, after Hunting the Daughter's resolution, Aroru's Reaction's delayed effect moves him, if his player chooses.
Unfortunately, even if you're a Crab player, you don't get your additional action until Aroru is already gone. Additional actions are delayed until after the opportunity to take Reactions triggered by the original action ending (see here), which is also after Aroru's delayed effect triggers.