|This article is about a/an episode in Choudenshi Bioman.|
Fight! Vow to the Planet (戦え！星に誓って Tatakae! Hoshi ni Sakatte) is the eighth episode of Choudenshi Bioman. This is the conclusion of the two-part story where Peebo discovers the fate of his friend Joy and the matters regarding the destruction of planet Bio.
As Peebo is forced to give up Bioman's secrets to Gear, the team rescues him as they decide to discover the harsh truth about Joy's ultimate fate.
With Peebo captured by the Neo Gear Empire, Mason wants Peebo to tell them what the Biomen's weakness is. Peebo of course refuses, so Mason tortures Peebo's friend which is painful for Peebo to watch, so he tells Mason what he wants to know. The Biomen manage to rescue Peebo, but he won't let his friend suffer the Empire's grip. The Biomen realize many things about Peebo's friend don't add up and that Peebo may be walking into a trap if the Biomen don't stop him. The Biomen help Peebo sneak into the Empire's base to discover Mechaclone blueprints of Peebo's friend. The robot then comes to the realization that message he received in the previous episode was fake! Peebo's friend is revealed for the Mechaclone he really is and explodes! The Biomen then make short work of Gear's latest giant mecha. But the threat of evil is far from over.
- Shirou Gou (郷 史朗 Gō Shirō): Ryōsuke Sakamoto (阪本 良介 Sakamoto Ryōsuke)
- Shingo Takasugi (高杉 真吾 Takasugi Shingo): Naoto Ōta (太田 直人 Ōta Naoto)
- Ryuuta Nanbara (南原 竜太 Nanbara Ryūta): Akito Ōsuga (大須賀 昭人 Ōsuga Akito)
- Mika Koizumi (小泉 ミカ Koizumi Mika): Yuki Yajima (矢島 由紀 Yajima Yuki)
- Mika Koizumi (Voice): Mayumi Tanaka (田中 真弓 Tanaka Mayumi)
- Hikaru Katsuragi (桂木 ひかる Katsuragi Hikaru): Michiko Makino (牧野 美千子 Makino Michiko)
- Peebo (ピーボ Pībo, Voice): Yoshiko Ōta (太田 淑子 Ōta Yoshiko)
- Doctor Man (ドクターマン Dokutā Man): Munemaru Kōda (幸田 宗丸 Kōda Munemaru)
- Mason (メイスン Meisun): Hirohisa Nakata (中田 博久 Nakata Hirohisa)
- Farrah (ファラ Fara): Yōko Asuka (飛鳥 裕子 Asuka Yōko)
- Monster (モンスター Monsutā): Strong Kongō (ストロング金剛 Sutorongu Kongō)
- Messerjū (メッサージュウ Messerjū, Voice): Shun Yashiro (八代 駿 Yashiro Shun)
- Viewership: 10.0%
Choudenshi Bioman Volume 1 features episodes 1-11.