Agent 21 anime

Dominion Tank Police

OVA / 4 eps / Spring 1988 / Manga

Leona Ozaki joins Newport City's infamous Tank Police division. With aid of Al and her newly built mini-tank, Bonaparte, she wages war on Buaku and his cohorts, the Puma Sisters. (Source: ANN)

Elf 17

OVA / 1 eps / Winter 1987 / Manga

Muscat Tyler is the 108th prince of the Galaxy Empire and is known as an eccentric person. He travels around the universe accompanying a Walking Arsenal, K.K, and Lu of the Light Wing Race, the strongest creature in the universe. Wherever they go, there is trouble. (Source: ANN)

Dragon Fist

OVA / 1 eps / Spring 1991 / Manga

The story follows Ling Fei-long, a Chinese transfer student living in Japan. Ling is the son of the leader of the White Dragon clan, one of four clans who live in the mountains of China and are descended from mythical beasts. After killing an ordinary human, Ling is banished to Japan so that he might learn about humanity and how to control his powers around them.

High School Agent

OVA / 2 eps / Summer 1987 / Manga

Based on a manga by Tanimura Hitoshi, serialized in Comic Burger. Teenager Kanemori Kousuke is a secret agent for the international VN spy network. Using his computer hacking skills, he tracks international criminals. Later he goes after Neo-Nazis to the Arctic were they try to raise a U-boat with a sinister secret. (Source: The Anime Encyclopedia)

Namakemono ga Miteta

OVA / 2 eps / Fall 1988 / Manga

Based off a manga by Murakami Takashi that was serialized in Weekly Young Jump. (Source: AniDB)