Tomorrow's Ace is You! (明日のエースは君だ! Ashita no ēsu wa Kimida!) is the fifty-second and final episode of Ultraman Ace.
Following the defeat of Geegon, Yapool's most recent Terrible-Monster creation, a juvenile Alien Simon appears on Earth. It turns out that this is yet another disguise of Yapool, and he is about to set in motion his ultimate plan; the creation of the chimeric monster Jumbo King! How will Ace fare against this final threat?
A flying saucer crashed after being hit by another from the back. While examining the saucer's remains, TAC discovered an Alien Simon and took it from the children playing as the Ultra Brothers. In the middle of returning to base, Yapool summoned the souls of the deceased Terrible-Monsters: Unitang, Cowra, Mazaron Man and Mazarius and fuse them into Jumbo King. As the TAC members fend for themselves, Hokuto spirited the young alien to the stable. Through their radio, Yapool demanded the young alien with their city's safety as a bargaining chip. Despite TAC's best effort to lure the Terrible-Monster away from the city, Jumbo King persist and destroyed half of it and spared the other half for the next day. The Alien Simon injured Hokuto on purpose and planned to surrender itself to spare the city from Yapool.
At TAC's headquarters, captain Goro Ryu explained that the formation of Jumbo King was made possible due to the fact that past monsters defeated by both Ultramen and attack teams had their molecules remained on Earth, thus Yapool was able to gather most of the defeated Terrible-Monsters in the past into his recent creation. In order to save both the city and the children's hearts, the captain suggest using a Cell Decomposition Missile despite being at the prototype stage. Outside, Yuko contacted Hokuto, and warned that should he get his identity exposed, the possibility exists that he may never be able to return as a human.
In the next day, TAC attempted to use the missile, but Jumbo King managed to resist and continue rampaging the second half of the city. While alone in the stable with a group of children, Hokuto noticed something amiss with Alien Simon's antenna. Jumbo King made its way to the stable and the occupants exited but it was at that moment when Yapool revealed himself underneath Alien Simon. Though Hokuto defeated Yapool, in the end he was forced to reveal himself as Ace's host to the children and TAC to regain their trust.
"In order to tell them the truth, this is the only option I had. Goodbye Earth, goodbye fellow TAC members, goodbye Seiji Hokuto."
- ―Ultraman Ace
After Hokuto transformed, Ace fought valiantly against Jumbo King and killed the last Terrible-Monster after a long struggle. However, his act of exposing his identity forced Hokuto to forsaken his humanity and prepared to leave Earth. After Ace giving a few parting words and flying towards the sunset, the children bid their farewell and the episode ended with shots of the TAC members.
"Don't lose your kindness. Take care of the weak and help each other. And don't stop trying to be friendly with people from other countries. No matter how many times you're disappointed. Those are my last wishes."
- ―Ultraman Ace.
- Seiji Hokuto (北斗 星司 Hokuto Seiji): Keiji Takamine (高峰 圭二 Takamine Keiji)
- Yuko Minami (南 夕子 Minami Yūko): Mitsuko Hoshi (星 光子 Hoshi Mitsuko)
- Gorō Ryū (竜 五郎 Ryū Gorō): Tetsurō Sagawa (瑳川 哲朗 Sagawa Tetsurō)
- Ichirō Yamanaka (山中 一郎 Yamanaka Ichirō): Shunichi Okita (沖田 駿一 Okita Shun'ichi)
- Tsutomu Konno (今野 勉 Kon'no Tsutomu): Masaaki Yamamoto (山本 正明 Yamamoto Masaaki)
- Noriko Mikawa (美川 のり子 Mikawa Noriko): Keiko Nishi (西 恵子 Nishi Keiko)
- Kōzō Yoshimura (吉村 公三 Yoshimura Kōzō): Mitsuhiro Sano (佐野 光洋 Sano Mitsuhiro)
- Yōichi Kaji (梶 洋一 Kaji Yōichi): Katsumi Nakayama (中山 克己 Nakayama Katsumi)
- Ultraman Ace (ウルトラマンA Urutoraman Ēsu): Goro Naya (納谷 悟朗 Naya Gorō)
- Yapool (ヤプール Yapūru) Hirofumi Takada (高田 裕史 Takada Hirofumi)
- Ultraman Ace Volume 13 features episodes 49-52.
- In the event of the 2019-20 coronavirus pandemic, this episode is the first one to be aired in YouTube as part of Tsuburaya's "#UltraScienceFantasyHour".
- In the scene before Alien Simon reveals his true identity when helped up, the suit actor's face could be seen in the mouth.