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.
Shinjo Naota is normally 4 Force, and his trait reads: Naota has +2F while a Terrain is in play at his battlefield.
Unfamiliar Ground reads: Terrain Battle: Bow each card with 5 or higher Force now at this battlefield. If a card's effect destroys this Terrain iduring this battle, straighten all cards it bowed.
Would playing Unfamiliar Ground bow him?
Would playing Unfamiliar Ground bow Shinjo Naota?
Yes. The terrrain has to enter play -- activating Naota's trait -- before any of its effects start resolving (http://rules.l5r.com/CE_Glossary_T#Terrain).