Shock
You see a mouth coming out of the top of a tree so you go into shock. Your brain just can't comprehend what's in front of you.
A tree... with... a... mouth? No, it can't be... I... a-. Your face warps into a permanent state of shock.
ほう
あき, おろか, ほけ, ぼ
None
The shock you've suffered results in you needing to stay home (ほう) from now on. You don't get to travel, explore, or even get groceries. You're homebound from now on, buddy.
I'd be shocked if you ever left your home again, honestly. But hey, there's always anime.