The 5 Ultra Oaths (ウルトラ5つの誓い Urutora Go tsu no Chikai) is the 51st and final episode of Return of Ultraman. It features the return of the monster Zetton from the Original Ultraman Series. The episode introduces The 5 Ultra Oaths.
Jiro and Rumiko are kidnapped by an alien. Ultraman and MAT must find a way to rescue them, but the infamous Zetton has arrived on earth.
Hideki Go is having recurring nightmares of the original Ultraman's imfamous final battle with Zetton. He wakes up and gets a call from an unknown figure. He is ordered to go to a baseball stadium. Meanwhile, Jiro, and Rumiko wake up in a baseball stadium and try to escape, but are stalled by Alien Bat.
Go arrives at the stadium, and encounters Zetton II, under Bat's control. Go tries to transform into Ultraman, but unable to. He hears the original Ultraman's voice and tells him that Zetton was the only monster that he couldn't defeat and if Go rushes in to battle he will lose just like him. Alien Bat then tells him of the Bat invasion of the Land of Light and that the Ultra Brothers will be unable to stop them. He threatens to unleash Zetton II on the city. An angered Go leaves abruptly.
Go reports his findings to his teammates at MAT, who decide to have one contingent fight Zetton, who is rampaging in the city, while another contingent rescues the Sakatas. MAT manages to rescue the Sakatas, but Go is shot down by Zetton. Meanwhile, Bat transforms into a giant and the duo start to continue to rampage throughout the city.
Ultraman Jack, touched by Go and MAT's courage allows the former to transform one last time.
With the assistance of MAT, Ultraman manages to stab Alien Bat and kill him. He then destroys Zetton with his Ultra Hurricane and Specium Ray, avenging the original Ultraman's defeat.
Go, presumed to be dead, has a funeral service held by MAT and the Sakatas near the ocean. When MAT leaves, Go appears to Jiro and Rumiko one last time. Go knows he needs to go to M78. He tells Jiro to recite the 5 Ultra Oaths but he refused to. Go saids goodbye to Jiro and transforms into Ultraman. Jiro shouts the 5 Ultra Oaths at both Go and Ultraman while they vanish into the sky and return to to M78.
- Hideki Go (郷 秀樹 Gō Hideki): Jiro Dan (団 時朗 Dan Jirō)
- Ryu Ibuki (伊吹 竜 Ibuki Ryu): Negami Atsushi (根上 淳 Negami Atsushi)
- Takeshi Minami (南 猛 Minami Takeshi): Shunsuke Ikeda (池田 駿介 Ikeda Shunsuke)
- Ippei Ueno (上野 一平 Uneo Ippei): Hatashi Mitsushi (三井 恒 Mitsushi Hatashi)
- Yuriko Oka (丘 ユリ子 Oka Yuriko): Mika Katsuragi (桂木美加 Katauragi Mika)
- Fumio Kishida (岸田文夫 Kishida Fumo): Ken Nishida (西田健 Nishida Ken)
- Jiro Sakata (坂田 次郎 Sakata Jirō): Kawaguchi Hideki (川口英樹 Hideki Kawaguchi)
- Rumiko Maruno (村野 ルミ子 Maruno Rumiko): Iwasaki Kazuko ( 和子 岩崎 Kazuko Iwasaki)
- The Original Ultraman (初代ウルトラマン Shōdai Urutoraman Voice), & Ultraman (ウルトラマン Urutoraman Voice): Isao Yatsu (谷津勲 Yatsu Isao)
- Alien Bat (バット星人 Batto Seijin Voice): Osamu Saka (阪 脩 Osamu Saka)
- Narrator (ナレーター Nareta): Akira Nagoya (名古屋章 Nagoya Akira)
- MAT Commander Worker: Eiichi Kikuchi (菊池英一 Kikuchi Eiichi)
- Return of Ultraman Volume 13 Features Episodes 49-51.
- With a rating of 29.5%, this is the highest rated episode of Return of Ultraman.
- Stock footage from the final episode of Ultraman is used when Go is dreaming of the Original Ultraman fighting Zetton.
- Ultraseven and Zoffy are mentioned by Alien Bat.
- With this episode Jack and the previous Ultra Warriors are referred to as the Ultra Brothers for the first time.
- In the original version when Ultraman Jack does his pose at the end of the episode the sky is afternoon, but in the HD Verison the sky is blue.