Here are some Rewrite Quest Voice clips detailing Chihaya’s love for lumber.
Akane: Chihaya, why are you trying to change your equipment. Your weapon is this piece of lumber.
Chihaya: You know, it would be great if I could have a normal weapon like a long sword.
Kotarou: No, use lumber.
Chihaya: Why does it have to be lumber!?
Akane: Hey… There’s a piece of lumber over there. Are you going to get it?
Chihaya: Why are you asking me?