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.
In several recent games of mine there have been some debate due to the Tachikaze being in play, and/or the new Expendable Keyword.
If a personality with followers attached has a Strategic Strike performed on them, are they "destroyed" or "discarded?"
This is the relevant paragraph of the CR pertaining your question (you need to scroll down a bit):
When a Personality leaves play, all his attached cards leave play in the same manner as he did. This leaving play is a rulebook effect contingent on the effect that took the Personality out of play, so the attachments are destroyed "for" (as a consequence of) the original effect, but not "by" the original effect.
(Emphasis mine)
With regards to Tachikaze, the answer is "it is irrelevant". Tachikaze reads: "After an action resolves whose effects destroyed your Follower with a Gold Cost of 1 or more: You may put it face-up under this card." (Emphasis mine) The action's effects aren't the cause of the Follower leaving play (they aren't destroyed *by* the card effect, as in the above quote, but rather by the rulebook), so Tachikaze won't work. The action's effects must directly destroy the Follower, not just its Personality.
In reference to the Expendable keyword, you'll draw a card. When the Personality is destroyed, the attachments leave play "in the same manner", ie they are also destroyed and the Expendable keyword on them is triggered.