Godzilla Junior

Godzilla Junior (ゴジラジュニア, 'Gojira Jyunia'), also known as "Baby" and "Little One", is the adopted son of Godzilla featured in the last three movies of the Heisei Godzilla series. Asuza Gojo and Miki Saegusa acted as mother figures to him in the first film. He had the longest screen time for a kaiju in any Godzilla film (almost the entire duration of Godzilla vs. Mechagodzilla II .) He was portrayed by suit-mation actor "Hurricane" Ryu, who previously played King Ghidorah and Battra.

Baby Godzilla
Baby Godzilla's (ベビーゴジラ, 'Bebii Gojira') first appearance was in the 1993 film Godzilla vs. MechaGodzilla II. Baby Godzilla's egg was found on Adona Island with a hatched Rodan egg. The Rodan had since looked after the unhatched egg. Godzilla himself looked to have interest in the egg, but Rodan fought Godzilla to protect the egg (and failed). However, scientists took the egg during the fight. Godzilla then went to Japan to get the egg. The egg hatched and much to the scientists' surprise, it was an infant Godzilla. When examining the infant, they found out that he had a second brain in his hip. This led the scientists to suspect that Godzilla must have a second brain as well. So they modified Mechagodzilla to attack this weak point. But Rodan came in his fire form to fight Mechagodzilla and fought well but failed. Godzilla arrived soon after and fought Mechagodzilla, nearly destroying the mech. But the scientists upgraded Mechagodzilla into Super Mechagodzilla and it succeeds to destroying Godzilla's second brain. Godzilla is almost killed, but listening to Baby Godzilla's cry, Fire Rodan gives up his life essence to Godzilla and disappears. A newly revived Godzilla destroys Mechagodzilla with his new Spiral Atomic ray. Baby Godzilla and his new father swim off to sea to find a new home.

Little Godzilla
By 1995 (Godzilla vs. SpaceGodzilla), Baby Godzilla had grown to 30 meters in height (almost 1/3 the height of his adopted father) and is now known as Little Godzilla (リトルゴジラ, 'Ritoru Gojira'). Although the creature is only about one year old, exposure to Godzilla's radioactivity rapidly increased his size and stunted his natural growth, giving the young kaiju his bizarre appearance. Little Godzilla also displays the ability to fire a weak energy beam like his father, although this "beam" takes the form of glowing dust or bubbles. (This ability mirrors Minilla's famous smoke rings from the Showa series). After the events of Godzilla vs Mechagodzilla II, both Godzilla and his new "son" arrive on Birth Island in the South Pacific. While Godzilla remains predominantly underwater off the coast, Birth Island itself becomes Little Godzilla's permanent home. When a team from Japan's Counter-Godzilla Center (U.N.G.C.C.) arrives on the island to conduct an experiment in psychically controlling Godzilla (known as Project-T), they encounter Little Godzilla playing about the small, tropical paradise. At one point, the infant monster accidentally sets off a series of tear-gas mines placed along the coast. Later, after the T-Project has been tested on the adult Godzilla, the monster SpaceGodzilla arrives on Earth and lands on Birth Island, right before a terrified Little Godzilla's eyes. At first the young creature hides in fear, but he soon ventures out and attempts to investigate the strange beast. Spacegodzilla, however, unleashes his powerful Corona Beam and attacks the young monster heartlessly. As Little Godzilla attempts to crawl away, his father arrives to defend him. The adult Godzilla, unfortunately, is no match for his cosmic clone, and is soundly defeated. Before departing, Spacegodzilla telekinetically lifts Little Godzilla from the ground and then imprisons him within a cage of crystal spires. Only after Godzilla and M.O.G.U.E.R.A. were able to defeat Spacegodzilla in Fukuoka did the little kaiju walk free from his crystal prison.

Godzilla Junior
In 1996, one year after Godzilla defeated SpaceGodzilla, the King of the Monsters' nuclear energy begins to run out of control. His rising temperature causes uranium deposits on Birth Island to ignite, destroying the tropical paradise. Although Godzilla soon surfaces, Little Godzilla remains missing and is presumed dead. He is finally located, but the immense radioactivity released during Birth Island's destruction mutated the young monster even further. Now standing 40 meters in height, and bearing a strong resemblance to his father, the kaiju is now dubbed "Godzilla Junior". The much smaller Godzilla is discovered to be traveling to Adonoa Island, where his egg was discovered two years earlier. Unfortunately, it is also discovered that the adult Godzilla is following Junior from a distance. With his meltdown estimated to take place only seven days later, the U.N.G.C.C. know that Godzilla will never make it. At the same time in Japan, a creature created by Dr. Serizawa's Oxygen Destroyer is unleashed. The G-Force devise a plan to somehow pit Godzilla against this new monster, dubbed Destoroyah, in hopes that Godzilla will be killed in the same way his predecessor was in 1954. To do this, they conscript the two psychics Meru Osawa and Miki Saegusa to lure Junior to Tokyo, and hope Godzilla will follow. Junior is successfully lured to Destoroyah's position and attacks the giant crab-like creature with all he has. However, the young monster is knocked aside by Destoroyah and pinned down under the beast. Destoroyah then sinks it's mandibles into Junior's chest and injects micro-oxygen into the deep wound. Junior, however, finds the strength to retaliate and blasts Destoroyah away with his atomic ray at point-blank range. The Precambrian creature degenerates and breaks down as it falls, defeated, into an oil refinery. The refinery explodes, and Junior roars in victory. That night, Godzilla finally arrives and greets his adopted son on the outskirts of Tokyo.

Suddenly, Destoroyah rises from the burning refinery in it's final, demonic form. The mutant beast takes flight and knocks Godzilla down. The monster then grabs Junior, dropping him in a building, and blasts him with his micro-oxygen beam, killing the young monster. Saegusa and Godzilla were very heartbroken for the death of Godzilla Junior, as they both knew another kaiju will die: Godzilla. With aid from the military, Godzilla succeeds in finally killing Destoroyah and then melts down. Radiation filled to skies of Japan turning it into a ghost city, but the radiation is absorbed when Junior rises, all grown-up and fully developed into an adult Godzilla, showing that Godzilla's legacy will never end. Godzilla Jr looks almost identical to his dad.