Hoshi wo Machigaeta Onna(1978)

Konma comes from a distant planet, Mango, and gets lost on a trip to subspace, landing on Earth, where she meets Momiage, an editor she met in town, and ends up working as an assistant to Matsui, a female manga artist. Eventually, Konma's interest in shoujo manga leads to a series of outlandish incidents involving Matsui-sensei and Momiage.