Ken Sato

Kenji's father, Hayao, hoped his son would become the next Ultraman, following in his heroic footsteps. However, his mother, Emiko, insisted that Kenji become an outstanding baseball player. One night, Gigantron's attack finally changed the fate of this family. Due to frequent Kaiju attacks in Japan, Kenji's parents decided to separate. Kenji moved to Los Angeles, United States, with his mother, while his father, Hayao, stayed in Tokyo.
This disorder left young Kenji confused and hurt, unable to understand the reasons behind his parents' separation. He began to believe that his father had abandoned him and his mother to pursue a career as a kaiju researcher and as an Ultraman. This belief left a deep mark on his adult psyche, causing him to tire of the prospect of becoming Ultraman and instead focus on his baseball career, all while distancing himself from his father. Despite everything, Kenji still inherited Ultraman's abilities from his father.

Twenty years later, Kenji finally realized his dream of becoming a baseball player. As a star player for the Los Angeles Dodgers in Major League Baseball, he was active in the baseball world under the name "Ken Sato." With his outstanding performance, he won numerous honors, including the Gold Glove Award and the Silver Slugger Award. Throughout his baseball career, Ken achieved notable results, with a 420 batting average and 624 successful stolen bases. However, he never managed to win a championship. Ken chose to stay away from the media spotlight, avoiding multiple interviews and maintaining a certain distance from his teammates. The deep pain and misunderstanding regarding his father, along with the difficulties he faced adapting to the new environment after moving to the United States, made it difficult for him to fully open up. In spite of the

A few months later, when Hayao was injured and could no longer fulfill his duties as an Ultraman, he contacted Ken and Emiko, hoping that Ken could assume his identity in order to protect Japan. This meant that Ken would have to take on the role of an Ultraman, destined to shoulder the responsibility of saving the world. Emiko backed this plan, and wished for Ken to adapt well to his new life in Tokyo. However, one day, Emiko disappeared in an accident and was not heard from for a long time, plunging Ken into immense grief. He sought out Mina's help, asking her to track his mother's last known GPS location, but to no avail. His mother's disappearance became an unhealed wound in his heart.
Amidst complex emotions, Ken reluctantly abandoned his life in the United States and returned to Japan. He took up residence in a base near Tokyo Bay called "Ultrabase" and, under the pretext of playing for the team, joined the Yomiuri Giants. This sudden move attracted significant attention from the mainstream sports media in Japan. At the press conference, Ken displayed an extremely arrogant and boastful attitude, constantly bragging about his athletic abilities and vowing to lead the struggling Yomiuri Giants back to the top. However, a sports journalist named Ami Wakita noticed his actions. When Ami asked if Ken had returned to Japan due to the "emotional strain of losing a family member", Ken avoided the question and quickly left.

After inheriting his father's powers, Ken became the new Ultraman and began fighting off Kaiju attacks in his role as the current Ultraman. However, initially as a rookie, he lacked the determination, maturity, and sense of responsibility needed to effectively repel the Kaiju. Consequently, he frequently faced counterattacks from the Kaiju during various battles and was even ignored by the quasi-military organization KDF, whose primary goal was to eradicate Kaiju threats.

After the battle with Neronga concluded, Ken went to meet journalist Ami for an interview as scheduled. They had a deep conversation at a soba shop, during which Ami's questions gradually caused Kenji to begin to question his own choices. He realized that he had been unaware of the damage caused to the surrounding environment and innocent civilians during his battles. Furthermore, the Japanese traditionally expect Ultraman to take on Kaiju with minimal collateral damage, a concept that Ken had a hard time grasping. He remained more interested in his baseball career, and viewed "becoming Ultraman" as an unnecessary source of pressure that he wanted to avoid. During the baseball competition, Ken's American-style attitude and behavior clashed with the atmosphere of Japanese baseball. Furthermore, his aloofness towards the other team members and their skills made him a target of ridicule by opposing players.

One day, Ken headed to the New Tokyo Dome for his first match of the season as a star player. However, midway through the match, Gigantron suddenly crashed into the stadium, attempting to seize an object closely guarded by the KDF. Ken had no choice but to abandon the game, transform into Ultraman to chase after Gigantron, and attempt to stop the KDF air force from attacking Gigantron. In the end, both he and Gigantron were hit by missiles and fell into Tokyo Bay.

Sunmin Ultraman Inn
Ultraman/Ken witnesses Emi's birth.
When Ken regained consciousness, he found himself lying next to the unconscious Gigantron and saw the object that KDF had been chasing. When the object's steel casing peeled off, it revealed a Gigantron egg. As he watched it intently, the egg unexpectedly hatched into a "baby". With KDF still actively searching for the egg, Ken's protective instincts kicked in. He decided to protect this baby Kaiju and brought it back to his own base. Ken had not considered the consequences of bringing the baby Kaiju home beforehand. Soon, he found himself having to take care of the baby because it began to view Ken as its "mother". Despite keeping an eye on this dependent life, Ken resisted the role of "Kaiju caretaker". He wished to send the baby to the legendary "Kaiju Island", even though no one knew its whereabouts. With no other choice, Ken could only keep the baby confined in his underground base. During this time, Hayao witnessed the moment Gigantron was taken down and urgently contacted Ken, heading to his home. However, due to the long distance and misunderstandings, Ken vehemently refused his father's help and eventually watched his heartbroken father drift away. Under the mental stress of caring for Emi, Ken's performance in baseball began to decline. He realized that he couldn't handle both responsibilities at once.

However, the problems were far from over. Despite Mina’s help, Ken struggled to maintain balance while caring for the baby. He had to juggle daily concerns for the baby’s well-being with the demands of team training and matches. Under the double pressure, both physical and mental, his performance began to slip, earning him criticism from the public and even stern warnings from Coach Shimura. After three months of struggle, Ken finally broke down, realizing he couldn’t juggle both roles simultaneously and crying uncontrollably.