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.
Lady of the Forest Sensei reads
All Clans. Sensei Your Fox Clan Personalities have your Clan's trait. Whenever a Creature or Forest card is destroyed, lose 1 Honor.
Shiro Usagi reads
Your Clan alignment is Hare Clan. Hare Clan Personalities you own have your Clan alignment.
If I am running the pair together in a Legacy/Open event, do my Fox Clan Personalities gain the Hare Clan trait?
Lady of the Forest Sensei + Shiro Usagi: If I am running the pair together in a Legacy/Open event, do my Fox Clan Personalities gain the Hare Clan trait?
Tentatively, Shiro Usagi cannot use "all clans" sensei (which effectively means, "No sensei," I suppose). When printed, "clan" meant "faction as specified in the rulebook," and Hare was not and is not a faction.