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, 2 April 2013
Otomo Sensei Reaction: Any number of times per turn, after a player chooses a card for which he searched his deck or discard pile, remove a card in your hand from the game: Remove the searched-for card from the game.
From the rules on Searching: If an effect searches for a specific card (such as "Ring of Water") or card-type (such as "a Ring"), the player must show it if he chooses to retrieve it, to verify that he has retrieved the appropriate card or type, even if the search effect does not specify it is shown.
I'm not entirely sure where the showing occurs in the timing sequence, so I figure I'll just ask. Assuming you're searching for something that would require showing for verification, is that card shown before the decision about whether to Otomoize it is made? (Tentatively, my thought is yes; I think that both the reaction and the showing have the same timing window, but traits precede reactions.)
Jon Palmer (rules official), 2 April 2013
Otomo Sensei Reaction: Any number of times per turn, after a player chooses a card for which he searched his deck or discard pile, remove a card in your hand from the game: Remove the searched-for card from the game.
From the rules on Searching: If an effect searches for a specific card (such as "Ring of Water") or card-type (such as "a Ring"), the player must show it if he chooses to retrieve it, to verify that he has retrieved the appropriate card or type, even if the search effect does not specify it is shown.
I'm not entirely sure where the showing occurs in the timing sequence, so I figure I'll just ask. Assuming you're searching for something that would require showing for verification, is that card shown before the decision about whether to Otomoize it is made? (Tentatively, my thought is yes; I think that both the reaction and the showing have the same timing window, but traits precede reactions.)
Yes. Showing is part of the Search effect, so it will happen before Otomo's reaction trigger.