Sound (ひびき～響～ Hibiki) is the eighth episode of Ultraman Orb THE ORIGIN SAGA.
Amate sensed that Psychi is not only heading to Earth, but also to the man she was connected to, Shohei. Gai leaves the Planet Kanon to his seniors' care while he left to pursue the mad scientist alone. On Earth, the researchers prepare to evacuate when the Tree of Life's seed begins to sprout but Shohei was visited by Amate spiritually, who told him that the Bezelbs are after his life before leaving for good. With no ways to stop the roots from spreading, a strange man (who did confirms himself as the giant of light upon being asked by Shohei) brought them to safety via Repulsor Lift system.
Shohei told the man of how it all began while the latter revealed that he was called to protect the Tree of Life by the will of the Earth. But the "giant of light" Amate referred to is Gai, who had just arrived on Earth. Gai introduced himself as Ultraman Orb while the stranger reveals himself as Gamu Takayama/Ultraman Gaia. Back on Kanon, Amate reassured to her people that although the Tree of Life disappeared, their planet would not perish due to the tree sprouting in another planet while Shinra reassured that their country shall be rebuilt in a short time. On Earth, with the reveal that the Tree of Life can evolve species, Gamu revealed that Shohei's contact with its seed has caused his pineal gland to activate, allowing him to contact Amate even if their distances are simply 70,000 light years apart. Having studied human evolutions, Gamu revealed that this tree might have played a part in human evolution due to its importance to the universe. As soon as the one in Kanon destroyed, it began sprouting on Earth thanks to Shohei's connection to Amate, otherwise the branch would have lost forever. A puzzled Yui wondered if Earth is the only planet with another seed, Gamu revealed that the Tree of Life already disperse its seed to various places in the universe.
Meanwhile, Psychi already made his way to Earth and witnesses its ongoing war amongst humanity. The next day, the Tree of Life had finished grown and several scientists try to examine it. Shohei tries to warn them to get away but only with the Bezelb's appearance convince them and the youth was kidnapped by it. Sensing Shohei in danger, Amate decided to depart to Earth while Ricca and Shinra joined her. Orb and Gaia appeared as they save Shohei and eliminated several of the Bezelb platoon. After saving Shohei, Bezelb try to stab Orb on the back but was saved by Juggler without notice. Once regrouping, the young man told Gai of who was his savior back then.
Having arrived on Earth, Juggler tries to decimate the giant Bezelb but fell into the sea. The sea divided and a blue giant unveiled himself.
- Gai Kurenai (クレナイ・ガイ Kurenai Gai): Hideo Ishiguro (石黒 英雄 Ishiguro Hideo)
- Jugglus Juggler (ジャグラスジャグラー Jagurasu Jagurā): Takaya Aoyagi (青柳 尊哉 Aoyagi Takaya)
- Amate (アマテ Amate): Saki Fukuda (福田 沙紀 Fukuda Saki)
- Ricca (リッカ Rikka): Asuka Shibuya (渋谷 飛鳥 Shibuya Asuka)
- Shohei Moriwaki (森脇 翔平 Moriwaki Shōhei): Yasuhisa Furuhara (古原 靖久 Furuhara Yasuhisa)
- Yui Nishioka (西岡 結衣 Nishioka Yui): Karen Miyazaki (宮﨑 香蓮 Miyazaki Karen)
- Shinra (シンラ Shinra): Yasuyuki Maekawa (前川 泰之 Maekawa Yasuyuki)
- Raigo (ライゴウ Raigou): Takaaki Enoki (榎木 孝明 Enoki Takaaki)
- Psychi (サイキ Saiki): Motoya Izumi (和泉 元彌 Izumi Motoya)
- Shin Asuka/Ultraman Dyna (アスカ・シン/ウルトラマンダイナ Asuka Shin/Urutoraman Daina): Takeshi Tsuruno (つるの 剛士 Tsuruno Takeshi)
- Musashi Haruno/Ultraman Cosmos (春野 ムサシ/ウルトラマンコスモス Haruno Musashi/Urutoraman Kosumosu): Taiyo Sugiura (杉浦 太陽 Sugiura Taiyo)
- Gamu Takayama/Ultraman Gaia (高山 我夢/ウルトラマンガイア Takayama Gamu/Urutoraman Gaia): Takeshi Yoshioka (吉岡 毅志 Yoshioka Takeshi)
- Bugen (ブゲン Bugen): Takeyuki Yue (湯江 健幸 Yue Takeyuki)
- Yosuke Aoi (青井 洋介 Aoi Yōsuke): Mister Chin (ミスターちん Misutā Chin)
- Partel (パーテル Pāteru): Riho Iida (飯田里穂 Īda Riho)