I Don't Understand Her Facial Expression at All (Pre-Serialization)

Yotsuya-kun fell in love with a student from his class, Shirogane-san, yet he can't read her facial expressions at all and she always wears a mask, so he tries to ask her for the reason. The Twitter web comic pre-serialization of [Hyoujou ga Issai Wakaranai Shirogane-san].