A Soldier's Back (戦士の背中 Senshi no Senaka) is the fifteenth episode of Ultraman X. This features the first episode of the third and final arc of this series.
Captain Kamiki attends his daughter's wedding but at the same time, Gomess appeared and worse, the monster was charged with the Dark Thunder Energy.
In the early morning, a monster appeared and terrorizes the countryside. Xio members are put to investigate the matters. Captain Kamiki receives a letter from his daughter, Hiromi whom invites him to her wedding. He feels hesitated, thinking that his relationship with his daughter deteriorates but Dept. Captain Sayuri assures him. Based on Daichi's research, the monster was named Gomess and the team gets to learn of Kamiki's past from Sayuri.
Meeting his daughter, he learns that preparations for her marriage were all done by her fiancé's parents. Kamiki flashes back into the past years where both him and Hiromi visited his bedridden wife at a hospital. While Hiromi prepared to draw a picture for her mother, the hospital's power source deactivates and a telephone call orders Kamiki to get into the action. His wife insisted him to go but Hiromi had a hard time leaving her father.
Gomess appears at area S2-6 and Xio takes action by evacuating the citizens and X fights the monster but before he can deliver the finishing blow, it quickly escapes by burrowing underground. Gomess stops burrowing and takes a rest at S2-9. The next day, Xio members plead him to go to Hiromi's wedding while they taking charge of the mission. But before Kamiki would leave the base, he senses something off with the atmosphere and orders Xio to investigate, and at that time, the Dark Thunder Energy strikes Gomess, turning into a rampant and granted it new powers. X appears and fight Gomess while Asuna tries to bring Cyber Gomora but injured from Gomess' attack.
Kamiki receives another flashbacks in the past where his wife and daughter were nowhere to be seen in the ward, with what's left was his daughter's drawing, Kamiki leaves for the battle and Hiromi's marriage takes place. Cyber Gomora appears, whose controller revealed to be Captain Kamiki and assist X in defeating Gomess. At last with the Dark Thunder Energy expelled, X and Cyber Gomora finishes the monster.
Kamiki arrives late at the wedding ceremony but his daughter appears, having waited for him and the two re-enact the marriage scene.
Daichi's Kaiju Lab
- Daichi: Daichi's Monster Lab! Today, we will get to learn about him.
- X Devizer: Analyzing Gomess...
- Daichi: Gomess is an ancient monster with incredible strength. It was empowered by the Dark Thunder Energy, and gained the ability to fire a high powered laser beam.
- X: And today's card is Cyber Gomess. After Gomess became an even greater threat, we had to work together with the Cyber Gomora, realized by Captain Kamiki to defeat it.
- Daichi and X: See you next time~
- Daichi Ozora (大空大地 Ōzora Daichi): Kensuke Takahashi (高橋健介 Takahashi Kensuke)
- Asuna Yamase (山瀬アスナ Yamase Asuna): Akane Sakanoue (坂ノ上茜 Sakanōe Akane)
- Wataru Kazama (風間ワタル Kazama Wataru): Yoshihiko Hosoda (細田よしひこ Hosoda Yoshihiko)
- Hayato Kijima (貴島ハヤト Kijima Hayato): Ukyou Matsumoto (松本享恭 Matsumoto Ukyou)
- Mamoru Mikazuki (三日月マモル Mikazuki Mamoru): Hayato Harada (原田隼人 Harada Hayato)
- Rui Takada (高田ルイ Takada Rui): Haruka Momokawa (百川晴香 Momokawa Haruka)
- Takeru Yamagishi (山岸タケル Yamagishi Takeru): TAKERU
- Chiaki Matsudo (松戸チアキ Matsudo Chiaki): Chiaki Seshimo (瀬下千晶 Seshimo Chiaki)
- Sayuri Tachibana (橘さゆり Tachibana Sayuri): Sarara Tsukifune (月船さらら Tsukifune Sarara)
- Shotaro Kamiki (神木正太郎 Kamiki Shōtarō): Yuu Kamio (神尾 佑 Kamio Yū)
- Ultraman X (ウルトラマンエックス Urutoraman Ekkusu): Yuichi Nakamura (中村悠一 Nakamura Yūichi)
- Xio equipments, X Devizer: Hibiku Yamamura (山村 響 Yamamura Hibiku)
- Ultraman X (ウルトラマンエックス Urutoraman Ekkusu): Sakaekei Iwata (岩田栄慶 Iwata Eikei]])
- Alien Fanton Gourman (ファントン星人グルマン Fanton Seijin Gourman): Hiroyuki Fukushima (福島弘之 Fukushima Hiroyuki)
- Cyber Gomora (サイバーゴモラ Saibā Gomora): Akira Okabe (岡部 暁 Okabe Akira)
- Gomess (S) (ゴメス(S) Gomesu (Esu)): Hiroyuki Arai (新井宏幸 Arai Hiroyuki)
- Ultraman X
- Bemstar Armor
- Gomess' appearance in this series is a tribute to Godzilla, who celebrated its birthday on November 3.
- Yasunori Matsumoto is absent in this episode, both as Gourman and the narrator.
- An actor allusion appears in this episode where X uses his shield as a boomerang appendage. This is a homage to Captain America from Marvel, as Steve Rogers/Captain America is voiced by Yuichi Nakamura (Ultraman X's voice actor) in the Japanese dub.