Demon Beast Invasion (Japanese: 妖獣教室, Hepburn: Yōjū Kyōshitsu) is a manga series written and illustrated by Toshio Maeda, published by Wani Magazine.

The series was adapted into a six-part original video animation of the same name in 1990, followed by Demon Beast Resurrection (妖獣教室外伝, Yōjū Kyōshitsu Gaiden) in 1995.

Millions of years ago, Earth was inhabited by a race of anthropomorphic giant monsters that can grow tentacles.

Following an ecological disaster, the Earth's atmosphere had started to become inappropriate for their cellular respiration and they migrated to the planet Quasar PHL-5200.

The story is centred on Muneto Ungyōsai and Kayō Asakura, two college students living in Tokyo.