The Eto Rangers ride in Space-Time Transmitting Machine Kirinda to repair the Novel Worlds of Mugen. The Eto Rangers themselves are anthropomorphic animals, each representing one of the 12 Chinese zodiac animals (and The Twelve Branches in Buddhism). In Japan they are known as the Eto animals. The Novel Worlds are stories created by the human imagination, such as old folk tales as well as newer books. These living worlds play out repeatedly, and are necessary for the good of humanity. Princess Aura rules Mugen, which is an island continent hanging over an ocean from the skybound Novel Pole. The Great God Goal gives her power, but she may never leave the small palace island area. Their nemesis is the forgotten Spirit of Cats, Nyanma (real name, Chocolat), who was excluded from the choice of 12 protectors by being disqualified from the race (in actual legend there are many versions of this story). She seeks her revenge by distorting Novel Worlds with Jarei Monsters. When a Jarei Monster goes to a Novel World they alter the story, turning it into a different version, sometimes a parody of itself. Bakumaru, the Spirit of Mice, must use the Genmakyou mirror to reveal ("Jarei Shouran!") the evil spirit once enough clues lead to its identity. Often the Eto Rangers must play out some of the story to find out who or what it is, sometimes even taking on the role of one of the characters in the tale. After defeating the creature, Kirinda is called when Bakumaru holds up his hand with one of Aura's 12 gems on it and calls out "Daikourin Kirinda!" Kirinda descends from a dimensional slit and purifies the evil spirit with a beam weapon, calling out "Jouka!" (Purification).

12 warriors who are burdened with the names of the 12 Chinese Zodiac members fight with each other's lives and pride at stake, all to grant just one wish.

12 warriors who are burdened with the names of the 12 Chinese Zodiac members fight with each other's lives and pride at stake, all to grant just one wish. (Source: ANN)

With the sudden appearance of the monsters that came to be called Dragons, the world had completely changed. Before long, within the human race supernatural girls with the power of the dragons, called "D," were born. The secret existence of the only male "D," the boy Mononobe Yuu, was forcefully thrown into the school where the girls of "D" gathered—Midgar, where he saw the naked body of one of the students, Iris. Furthermore, meeting his long-lost sister Mitsuki, Yuu seems to have been enrolled into this school...?! "When there's really no other choice, Iris, I will—kill you." "Can I really... believe you?" The curtains open as the "one and only story" about the boy who was supposed to become the strongest assassin and the incompetent girl unfolds—! Unlimited School Battle Action!

Chimera, a planet of beasts, is a prison planet for brutal criminals. Thor and Rai are twins, sons of an executive, brought up without wanting for anything. However, their father is murdered, and his murderers send the twins to Chimera. On this unforgiving world they will have to become beasts themselves just to survive.

Chase Suno and his friends, Jinja and Bren, are on a search for Chase's father, Jeredy Suno. However, they soon become involved in something else upon reaching their father's lab and becoming involved with an organism known as Monsuno. Chase, choosing to side with his father's work, denies S.T.O.R.M. access to the Monsuno and escapes. They are now on the run from the military organization, S.T.O.R.M., while still looking for Chase's father. However, a mysterious organization also has his eyes set on Chase and the group's Monsuno.

Chase Suno and his friends, Jinja and Bren, are on a search for Chase's father, Jeredy Suno. However, they soon become involved in something else upon reaching their father's lab and becoming involved with an organism known as Monsuno. Chase, choosing to side with his father's work, denies S.T.O.R.M. access to the Monsuno and escapes. They are now on the run from the military organization, S.T.O.R.M., while still looking for Chase's father. However, a mysterious organization also has his eyes set on Chase and the group's Monsuno.

Chase Suno and his friends, Jinja and Bren, are on a search for Chase's father, Jeredy Suno. However, they soon become involved in something else upon reaching their father's lab and becoming involved with an organism known as Monsuno. Chase, choosing to side with his father's work, denies S.T.O.R.M. access to the Monsuno and escapes. They are now on the run from the military organization, S.T.O.R.M., while still looking for Chase's father. However, a mysterious organization also has his eyes set on Chase and the group's Monsuno.

Chase Suno and his friends, Jinja and Bren, are on a search for Chase's father, Jeredy Suno. However, they soon become involved in something else upon reaching their father's lab and becoming involved with an organism known as Monsuno. Chase, choosing to side with his father's work, denies S.T.O.R.M. access to the Monsuno and escapes. They are now on the run from the military organization, S.T.O.R.M., while still looking for Chase's father. However, a mysterious organization also has his eyes set on Chase and the group's Monsuno.

In the year 3990, the immortal Oldna Poseidal rules Pentagona, a war-torn solar system of five planets. Daba Myroad is a survivor of the Yaman Clan, just one of numerous native societies nearly wiped out by the tyrant. Living on the remote planet Koam with his friend Mirao Kyao, Daba possesses L-Gaim, a humanoid mecha known commonly as a "Heavy Metal" and the last known relic of the Yaman Clan. The pair befriend Fanneria Amu, an aspiring actress, and Lilith Fau, the last surviving fairy in Pentagona while on the run from a band of thieves attempting to steal L-Gaim. Daba promises to fulfill the dying wish of one of the thieves hunting him—an honorable act that leads him to the powerful merchant Amandara Kamandara. With their mission in sight, the ragtag group will face powerful adversaries and become entangled in a rebellion against Poseidal's reign.

A recap OVA that portrays the first half of the series Heavy Metal L-Gaim. After the credits, there is a short clip animated for the OVA entitled "Lady Gavlet", which is intended to be comic relief.

A recap OVA that portrays the second half of the series Heavy Metal L-Gaim. After the credits, there is a short clip animated for the OVA entitled "Pentagona Dolls", which is intended to be comic relief.