Chiyuki-sensei wa Kara Mawaru

When their regular homeroom teacher is hospitalized, a substitute teacher arrives. This teacher is a snow woman with a strange constitution who melts and turns into a child when she gets nervous, only turning back into an adult after she cools down… And what's worse, she's a bit clumsy… Is this yuki-onna sensei going to be alright?

(Source: Magcomi, translated)