Amayo no Mayoi Neko

On a rainy night, protagonist Shin encounters a girl seeking shelter from the downpour. Her uniform is completely soaked, so kind-hearted Shin offers her his umbrella. But instead of using it, she silently follows him. Is this some new kind of stalker? Shin tries to run away, but can't shake her off... Thus begins an unusual cohabitation tale sparked by the rain.