If Ultraman Seven were left without the help of the Ultra Brothers and trapped by aliens, it would be a great loss. Thus, another Ultra Brother decided to stay on Earth, and it was Ultraman, the first to descend to Earth and guard it. His love for Earth was no less than Moroboshi's.
Reluctantly, Moroboshi arranged everything, took a long leave of absence from Mac's upper management claiming he needed to "go abroad" for recovery, and even integrated Hokuto Seiji and Hayata into Mac's team.
After making these arrangements, Moroboshi left Earth with Zoffy and headed to the M78 Nebula. At this time, without a brilliant scientist like Hikari, the capability of spatial warping had not been fully developed by the Ultras. The trip from the Land of Light to Earth required considerable time, usually utilizing specific wormholes to reach coordinates not far from each other in the cosmos.
Upon learning this, Chen Yu finally understood the mysteries that had puzzled him. Traveling at the speed of light from Earth to the Land of Light would take tens of thousands of years, which was impractical.
Chen Yu chose to stay on Earth instead of going with the Ultra Brothers. Moroboshi's residence was still available to him, but without Moroboshi, Chen Yu lost his source of living expenses. Now, he had to fend for himself in this world, relying on his legally processed identity by Moroboshi to avoid being undocumented.
In the following days, Chen Yu worked odd jobs while searching for a man named "Dan Moroboshi," only to find no trace of him, indicating Ultraman Leo had not arrived on Earth. Chen guessed that Leo might have gone to seek his brother, Astra, after the explosion of L77, Leo's only remaining kin.
Despite Moroboshi's departure, the appearance of monsters and aliens on Earth didn't decrease. However, with three Ultramen, including Chen Yu, Earth's safety was somewhat assured. Though he hadn't formally agreed to Moroboshi's requests, Chen Yu still fought to protect Earth, both to hone his skills and test the game "Ultraman Fighting Evolution."
After five monster and alien appearances with no new mission alerts from the game, Chen Yu found it odd. Typically, the game would detect a new monster and redefine the mission content and level. Chen speculated that the lack of new missions might be due to the incomplete task from the previous mission.
When Seven returned from the Land of Light fully recovered, he was eager to protect Earth and join the training of the cosmic martial arts Chen Yu had shared. Realizing Seven's enthusiasm, Chen Yu generously shared the cosmic martial arts knowledge with him.
After about a year of practice, Chen Yu mastered the cosmic martial arts, using various skillful moves against enemies and integrating them seamlessly into combat.