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, 23 July 2008
Lets K.I.S.S. this one.
Moto Yong Tai XP Says, Reaction: After an action resolves that moved a personality: Target and bow the personality. Straighten one of your target personalities.
Chagatai XP 4 says, Battle: Even if Chagatai is bowed or has been in battle resolution this turn: Move him to the current battlefield. If he is now opposed, straighten him.
Familiar Scenario, Chagatai goes into an unmanned province and decimates it. He then moves using his battle ability into an empty province. Can Moto Yong Tai target Chags, bow him then straighten him?
TL;DR Version; Even though you can't technically bow the already bowed Chagatai, the bowing isn't a cost, so would you still be able to straighten him using Moto Yong Tai's ability.
[mod edit -- thread title]
Brook Cunningham (rules official), 24 July 2008
Lets K.I.S.S. this one.
Moto Yong Tai XP Says, Reaction: After an action resolves that moved a personality: Target and bow the personality. Straighten one of your target personalities.
Chagatai XP 4 says, Battle: Even if Chagatai is bowed or has been in battle resolution this turn: Move him to the current battlefield. If he is now opposed, straighten him.
Familiar Scenario, Chagatai goes into an unmanned province and decimates it. He then moves using his battle ability into an empty province. Can Moto Yong Tai target Chags, bow him then straighten him?
TL;DR Version; Even though you can't technically bow the already bowed Chagatai, the bowing isn't a cost, so would you still be able to straighten him using Moto Yong Tai's ability.
[mod edit -- thread title]
I'm sorry, I couldn't parse all your acronyms above. And we, the Rules Team, do appreciate and encourage the use of complete card titles; in all your nicknaming of the Unicorn Champion, you never did get around to identifying him as a memmber of the Moto family.
But, bottom line:
The target of the second effect of Moto Yong-tai's action can be the same Personality that triggered it and was targeted by its first effect. This is because the two effects are not joined in the same sentence by "and" which would imply them to be different targets (as seen in this ruling about Daigotsu Exp 2). Thus, you could move one of your Personalities, react to his movement, bow him, and then straighten him.