On July 23, 2048, the Xorda attacked the planet Earth as a result of Dr. Ivan Kintobor's decision to dissect a Xorda emissary and use the knowledge to create the robot Isaac. Billions of humans were killed, and some survivors included people on a passenger craft which was in low Earth orbit during the attack. The ship crashed on a mountain, and its surviving population went on to form the hidden city of Station Square. There were other survivors gathered who were in shelters, as they were also taken to that one mountain in addition to other places.

Of all of the survivors, 10,000 of them were taken to a special laboratory where they were frozen for some time as part of a special experiment. The laboratory was part of Conservo, whose goal was to conserve mediums of Earth for those of the new world to see.

After thousands of years, the Conservo subjects were unfrozen around the Mobius year of 3232, as they were told they would receive financial assistance for housing, education, and more important needs under the United Federation.

Among the subjects were Katsumi Hideyoshi (秀吉勝巳), Hiroki Tenshin (弘輝天心), Shin Takeuchi (竹内新) and Miyuki Mizumaki (水木みゆき), all of them from Japan. The girls were 8 at the time as the boys were 9. They were to be taken to a city orphanage in Kenishira of the Fujiwara Unitary, but the ship they rode had crashed, and they were all thrown out of the aircraft before it hit the ground, critically injuring them.

The four were taken to a hospital in one of the UF cities, and at the hospital, it seemed they were very unlikely to survive their injuries. However, a scientist from somewhere said that he could do an experiment that would save their lives.

The scientist was revealed to be Lionel Hart, a lion scientist who had worked on many machines. He lives in the city of Orion along with his son Cyrus, which is located in the west of what used to be known as Florida to humans. The city also happened to be pretty close to the cities of Orlandi and Naomi, which are two UF cities made in tribute to two Florida cities. Since humans weren't too familiar with Mobians yet, Lionel asked to transfer them to a helipad where he could pick them up.

Lionel had a special machine that he could use to transfer Overlanders brains and DNA into cloned Mobian bodies, and he had a feeling it would work on humans too. He used the device to transform the injured four into Mobians, and based on pictures the children took holding animals, Katsumi became a brown cat, Hiroki became a red panda, Shin became a black monkey, and Miyuki became a purple otter.

The four woke up into their new bodies, and they were pretty freaked out at first. They would however get used to their bodies over time. They hung around the city for a while, and there they met Edwin Moore and Helena Simmons, who would train them to become fighters. They were also trained by Apollo Payne to use firearms and melee weapons. They were also given special holsters that would allow them to carry more weapons then they can usually hold, as they would be transferred from a special stronghold. The holsters could also give them more ammo when needed. They even learned to drive cars, as they would eventually get their own cars provided by a special friend that provided them with special tasks. They were even taught how to hot-wire cars. For some special tasks, they used special laser ammo that would stun victims rather than kill them, as it would usually be used on authorities.

With 3 years of training as well as doing special missions, they were professionals in the Mobius year of 3235. The four also became anti-heroes where they would do good and bad things. They also performed their first big heist in the city of Orion along with Edwin and Helena in the same year. They all split one half of the money, where the other half would go to charities as part of a taking from the rich and giving to the poor scheme. The four made about 10,000 each in the value of UFDs (United Federation Dollars).

Eventually, an Overlander man named Zander Yega became aware of the group of four and saw potential in them. He brought them to a Overlander state in the west, as he introduced himself as the ruler of the large state. They all got to look around his beautiful palace made of architecture that was computer-like. There was also gold and gems all over the place. They also got to meet the vice ruler of the city as well. They seemed trustworthy, and they were given a special task to go to a small Mobian village near a mountain. All of them prepared for the mission, and they were given more ammo and weapons to do so. They got to the village, and they weren't told what the mission was at first. When they were finally prepared, they were told to massacre the village as Yega has a world mission to cleanse the world of "corrupt" lifeforms. The four were shocked, and rather than doing what they were told, they refused. Yega responded by sending some troops to kill them and the villagers. They managed to fight back and kill all of the enemy troops and save all of the villagers. They knew they had someone to deal with, like how Sonic and his friends have to deal with Dr. Ivo Robotnik/Dr. Eggman.

They called themselves the Kasa-Obake Faitāzu (傘おばけファイターズ), as Hiroki lead the team. Over time, they explored the world of Mobius, did more heists, fought more terrorists, and did so much more. They even became more famous during Sonic's year in space starting in 3236, when they became special agents of the AII (Agency of Intelligence and Investigation) under Johnathan Walls, one of the higher ups under the director. The AII is part of the UF. They became celebrities, got richer over time, and even got some fancy sports cars they would drive around. However, the BIB (Beige Investigation Bureau), a Mobian agency similar to the AII, would become aware of them and try to catch them in certain events. They also got to know Geoffrey St. John and Hershey the Cat more (who were dating at the time), as they met before the Second Robotnik War of 3236 when the four were hospitalized in Mobotropolis. The two were concerned with their activities, and eventually they looked into their activities more.

Despite all of this, the four were still successful and became loved by many. They also made more friends along the way.