I Can't Hear Your Voice (キミの声が聞こえない Kimi no Koe ga Kikoenai) is the fifteenth episode of Ultraman Taiga.
Taiga has gone berserk after using the Kaiju Rings. Tregear's evil plot comes to fruition.
Hiroyuki opens his eyes up in a dark background, but suddenly, a mysterious mirror came to him, looking to it, revealing the disguised himself, removing the mask that revealed Kirisaki. Hiroyuki wakes up from a dream that a boy, Kanta, came to the company HQ before Homare, Pirika, and Kana went back to it. Kanta had like all of company to look for Moko, his Lunah friend. But for now, Hiroyuki will accept a boy's job offer but... members shouting to him, stopping that Moko is a boy's irreplaceable friend while "Shut up... Shut up already!" voice hearing in Hiroyuki's brain, but stopped. But before that, he has to take this job so a boy follows a member.
Hiroyuki sits under the bridge and beside Kanta, seeing a drawing Moko paper, while he puts it inside his pouch. He hears Moko's voice that he comes, followed by Hiroyuki. Pirika watches the footage: Moko hops on a ground that hits a phone, much to Kana's surprise. He and Kanta go to the abandoned building, but they take cover. An employee searches them that they're gone before he went up the stairs. He electrocuted by Hiroyuki, searching for Moko alone but Kanta waits. Hiroyuki saw many other captured kaijus. The two were apprehended by Chiburoids sent by Alien Chibull Mabuze, who contacted them via a hologram. He explained that he was capturing infant monsters in an attempt to create the ultimate creature. The Chiburoids were dealt with when Homare appeared, buying enough time for Hiroyuki to release Moko. Kirisaki conducts the Beethoven song, Symphony No. 9, he unleashed the genes of Gomora, Red King, and Belial, also known as the Cultivated Synthetic Monster, Skull Gomora.
Hiroyuki transforms into Taiga to do another battle, as a result of him using the Kaiju Rings, Taiga's fighting style becomes increasingly aggressive as he demands more power. After upgrading into Photon-Earth, he chops off Skull Gomora's horn and engages in what seemingly appears as a one-sided slaughter. Taiga also uses Gigadelos Ring to clone himself and blast the monster, before throwing into a building it and finishing it off with Aurum Strium. When enough darkness had accumulated within Taiga, Tregear takes the chance to corrupt him, shutting out Hiroyuki, Titas and Fuma in the process, much to Kana and Pirika watching.
Taiga becomes an unresponsive puppet which Tregear claims as his own partner, all just to spite Taro, much to Homare, Pirika, Kana, Kanta, and Moko sighting. Tregear gets the Rings from Taiga, fell unconscious, that as Taiga leads to the darkness, Titas and Fuma popped out into particles and Hiroyuki trapped into the black hole. Hiroyuki wakes up again that he saw Taiga, died and became the new member alongside Tregear but they can "Buddy Go". But then, as Homare and Kanta left, Hiroyuki sees Taiga one last time...
For Whom Is That Fist For - Part 3 (その拳は誰がために 後編 Sono Ken wa Dare ga Tame ni Kōhen)
Taiga finishes his story about his encounter with the Guar Army and Andro Ares.
- Hiroyuki Kudo (工藤ヒロユキ Kudō Hiroyuki): Yuki Inoue (井上 祐貴 Inoue Yūki)
- Homare Soya (宗谷ホマレ Sōya Homare): Ryotaro (諒太郎 Ryōtarō)
- Pirika Asahikawa (旭川ピリカ Asahikawa Pirika): Ayuri Yoshinaga (吉永 アユリ Yoshinaga Ayuri)
- Kana Sasaki (佐々木カナ Sasaki Kana): Chiharu Niyama (新山 千春 Nīyama Chiharu)
- Kirisaki (霧崎 ): Kou Nanase (七瀬 公 Nanase Kō)
- Ultraman Taiga (ウルトラマンタイガ Urutoraman Taiga): Takuma Terashima (寺島 拓篤 Terashima Takuma)
- Ultraman Titas (ウルトラマンタイタス Urutoraman Taitasu): Satoshi Hino (日野 聡 Hino Satoshi)
- Ultraman Fuma (ウルトラマンフーマ Urutoraman Fūma): Shota Hayama (葉山 翔太 Hayama Shōta)
- Ultraman Tregear (ウルトラマントレギア Urutoraman Toregia): Yuma Uchida (内田 雄馬 Uchida Yuma)
- Kanta (カンタ Kanta): Reo Masuda (増田 怜雄 Masuda Reo)
- Ultraman Taiga: Hideyoshi Iwata (岩田 栄慶 Iwata Hideyoshi)
- Ultraman Titas: Yoshiki Kuwahara (桑原 義樹 Kuwahara Yoshiki)
- Ultraman Fuma: Satoru Okabe (岡部 暁 Okabe Satoru)
- Ultraman Tregear: Shinnosuke Ishikawa (石川 真之介 Ishikawa Shinnosuke)
- Skull Gomora: Kenji Kajikawa (梶川 賢司 Kajikawa Kenji)
- Homare Soya
- Pirika Asahikawa
- Baby Samekujira
- Lim Eleking
- Baby Vadata
- Alien Galo
- Alien Chibull Mabuze
- Skull Gomora