Various characters from Go Nagai works including Devil Man, Mazinger, and Violence Jack, become trapped in a parody world where they all be come super deformed. They get trapped in this mishmash, fighting each other and are trying to figure a way back to their own world.

September 11, 197x, In the whole Kantou region a magnitude 8-9 violent earthquake occurred. Scholars called it the great destruction of the Showa Era, but the people called it the earthquake from hell! Volcanoes erupted, buildings crumbled, Tokyo became decimated in a single day. The government, after failing to recover the city, abandons Tokyo and moves the capital. The survivors form a society with no laws. In this harsh lawless world emerges Jack, a 10 foot giant who annihilates anyone and anything in his path. The manga details his journey. Note: This was the serialization in the magazine Weekly Shounen Magazine and Monthly Shounen Magazine.

Following an accident in the Himalayas, Akira Fudou's body has been taken over by none other than the fearsome demon, Devilman. However, upon living with Akira's relatives, Devilman has come to find himself rather fond of humanity - even if it means getting roughed up by his girlfriend, the Most Dangerous Miki Makimura for acting out, much to the Demon Lord Xenon's dismay. Wishing to kill the traitor, Xenon begins unleashing a series of cruel, grotesque demons unto Earth, and only Devilman stands between them and humanity's demise. Can the reluctant hero save his soul while keeping the city and his secret identity safe? 
(Source: Discotek Media)

From the island of Bardos in the Aegean Sea comes a new threat to humanity in the form of Doctor Hell and his army of mechanical beasts. However, a new hero stands in his way: Mazinger Z, a giant robot built out of the indestructible metal chogokin and equipped with an arsenal of advanced weaponry. Piloting Mazinger Z is hotheaded teenager Kouji Kabuto, who strives to avenge the death of his grandfather and protect Japan from Doctor Hell's forces.
 
(Source: Anime News Network)

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