What the fuck is a wood elemental? An inside joke from the VN...? I gotta hurry up and play that shit.
EDIT: Turns out it WAS an inside joke from the VN, and a pun in Japanese. 気のせい -> 木の精 (it's just your imagination -> wood elemental). Both of those kanji can be read "ki no sei." So when Sachi says "wood elemental" she means "it's just your imagination." Fucking wow, right? I didn't get it because I haven't played the VN and there was no text to go off, only her voice.
I'm not going to do a v2 because this joke is likely intended to be this way, since she deliberately says "wood elemental" in English. Translating its meaning would ruin the joke.
[Mori] Grisaia no Kajitsu Specials - 03 [BD][1080p].mkv (43.2 MiB)