Daichi and Asuna were sent on surveying a suburban area after a series of earthquakes reported. While patrolling, Daichi came across a mysterious woman. In addition, she appears every time the underground monster Telesdon emerges. While Telesdon retreated after being attacked with flares, Daichi and Asuna are task to discover the mysterious woman's identity. Said woman resembles an unknown civilian in real life, whom died sometime prior.
Hayato and Wataru visit Guruman in his room and asks him if the power of for Xio Blaster has been completed but to no avail, since Guruman is sleeping after eating his meal and according to Hayato, "There's nothing that can awaken an Alien Fanton once they fall asleep when taking a meal.". At the hanger, while helping maintenance crews on fixing the vehicles, Asuna contacts her mother and tells her that she will not returning home for now due to urgent business. Daichi arrives and send her a package she requested sometime prior, a pair of brand new shoes. She decides to use her day off tomorrow for salon, nail polishing and spa. Just then, the alarm rings and the two officers rush to command center. At Area T-7B, another earthquake reported as Daichi and Asuna goes to the Kamikura Station for investigation. While asking a pair of subway maintenance crews, the group hears a strange sound, followed by a disruption in the electrical supply and meets a strange woman in black. She screams and awaken a monster behind her as it emerges and attacks the city. Daichi scans and reveals it as Telesdon while he and Asuna engages into Land Musketty to attack it. However, Telesdon quickly grab the vehicle in its mouth and about to kill them with flames until Asuna releases flare bombs, scaring Telesdon and forcing it to retreat.
At the base, Xio members gets an intel of the strange woman, receiving reports that she had been sighted in several subway systems lately. Wataru deduces her as Underground Woman, the ghost woman that had been rumored on the internet. According to the urban legend, she always shown wandering in the subway and if a victim meets her, she will drag them underground and eats them. Sayuri orders everyone to get SNS data and footages from from every CCTV in the T-7B subway area. Daichi scans Telesdon from the footage and discovers that its frequency is that of anger. Sensing another frequency, he detects the source, the woman in black and finds its reading as sorrow. Rui visits Daichi's cubicle to reveal that adjustments on Cyber Eleking has completed. The woman in black has been identified with a similar civilian, Ryoko Mabuse, a beauty salon manager. With Sayuri requesting for someone to go undercover, Asuna proudly takes the offer and use that opportunity to wear her new shoes.
While going undercover with Daichi, they meet Ryoko at her salon, as Asuna reveals her as fake, since the real Ryoko died two months prior. Surprised by this, she attacks them and escapes, due to Asuna accidentally broke one of her new shoe's heels when running. Due to this, Asuna receives a bad complaint from Sayuri for her selfishness. Dr. Guruman awakens from his sleep and presents the power-up gadget for the Xio Blaster: Ultra Booster. He created it based on Ultraman X's power and thus, naming the combination Ultriser. While Daichi tries to keep X shut from revealing embarrassing things about Asuna, she reveals to Daichi the reason she wants to become more feminine: long ago, she took Kendo lessons from her father and beaten up one competitor (whom turned out to be her childhood crush), thus ruining her first love. Soon, another earthquake appear at area T-6C and the source is heading towards Kamikura Station and Capt. Shotaro sends Hayato and Wataru into action.
Spotting the Underground Woman, Asuna and Daichi try to attack but she summons Telesdon and orders it to attack the town for brighting the night with "fake lights". Asuna was knocked down from Telesdon's attack, forcing Daichi to become Ultraman X. X tries to fight but Telesdon manages to overpower and weaken him. Reinforcements arrives in the form of Hayato and Wataru, as the two uses the new Ultlaser to free X and the lab team delivers Cyber Eleking Card for X to use, becoming Eleking Armor. Using it, X turn the tables of the battle and finishes Telesdon with Eleking Electric Shockwave. While Daichi regroups with the others, the Underground Woman appears again but as Hayato and Wataru attacks, she vanishes, leaving behind her sunglasses and the Telesdon Spark Doll. Daichi recounts that he found a 500-year-old monument at the Kamikura Subway, hinting that it may be erected several years ago to seal something.
Daichi, Wataru and Hayato celebrate Asuna's birthday as they present her with a pair of new shoes brought by Sayuri, cheering her up. As X asks how old she is, Daichi quickly silence him, not wanting them to know his secret.
Daichi's Monster Lab
- Daichi: Daichi's Monster Lab! Today, we met this monster.
- X Devizer: Analyzing; Telesdon!
- Daichi: The Underground Monster, Telesdon. It wreaks havoc with its lava breath. You have to watch out for its spinning drill attack, too.
- X: And this card is Cyber Eleking.
- Daichi: With the Eleking Armor, you can control the electricity!
- X: Its finisher attack is Eleking Eletric Shockwave! Well? Pretty cool, right?
- 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 Voice): Yuichi Nakamura (中村悠一 Nakamura Yūichi)
- Ultraman X (ウルトラマンエックス Urutoraman Ekkusu Suit Actor): Sakaekei Iwata (岩田栄慶 Iwata Eikei)
- Alien Fanton Guruman (ファントン星人グルマン Fanton Seijin Guruman Voice): Yasunori Matsumoto (松本保典 Matsumoto Yasunori)
- Alien Fanton Guruman (ファントン星人グルマン Fanton Seijin Guruman Suit Actor): Hiroyuki Fukushima (福島弘之 Fukushima Hiroyuki)
- Ryoko Mabuse / Underground Woman (間伏涼子 / 地底女 Mabuse Ryoko / Chitei Onna): Hinako Saeki (佐伯 日菜子 Saeki Hinako)
- Telesdon (テレスドン Teresudon Suit Actor): Kazunori Yokoo (横尾和則 Yokoo Kazunori)
- Ultraman X
- Eleking Armor (First appearance)
- Alien Fanton Guruman
- Telesdon (Reintroduced and only appearance)
- Underground Woman (Reintroduced and only appearance)
- Cyber Eleking (Card only)