Fierce Battle of Colossal Beasts: Steel Devil) is a 1987 Japanese original video animation.

The plot is that of Takuya who visits a research center to meet an old friend, and their mutual connection with an experiment three years ago.

Rui, a girl who works at the center says that Haruka has been acting very strange lately, and isolates himself in the lab for weeks.

He breaks into the director's lab with the help of a friend and examines files relating to Haruka's research.

In an attempt to control the situation, the center's director orders the military to fire the laser canon on the island.

The OVA ends with Takuya awakening on debris floating in water.