|This article is about a/an episode in Tokumei Sentai Go-Busters.|
Mission 21: Farewell, Blue Buster (さらば ブルーバスター Saraba Burū Basutā) is the twenty-first episode of Tokumei Sentai Go-Busters
Ryuji's Weakpoint begins to severely harm his internal body, putting his life in serious danger if he ever fights the Vaglass again. And with the latest Metaloid themed after exercise equipment, it seems that it is not a easy challenge for Ryuji Iwasaki.
Finding the Energy Management Center base's air conditioner on the fritz, Hiromu and Yoko find Ryuji overheating before he loses consciousness. After the others get him to the medical ward, having met Masato earlier, Gorisaki frets when told by the man that Ryuji's inclusive medical checkup says he might die the next time he hits his Weakpoint.
Hiromu and Yoko come up with a plan to save Ryuji before they are deployed to the Nakaya district where they face off against Dumbbellloid before they find themselves exercising against their will, allowing the Metaloid to escape. Soon after, after playing the age card, Hiromu convinces Kuroki to make Morishita the new Blue Buster, much to Ryuji's dismay. After the others train Morishita, telling him and Nakamura what they have learned, Hiromu and Yoko are alerted to the Rindo district where Dumbbellloid calls them out, as Beet Buster and Stag Buster join the fight.
With Stag Buster forced into exercising, the others battle Dumbbellloid as Buddyloids enter the Buster Machines to face the Vaglass Megazord within 10 minutes' time. Overhearing Nakamura telling Kuroki of his condition, a speechless Ryuji takes his Buster Gear back to join the fight. Even after being told this might be his last fight and he can choose how he goes, Ryuji becomes Blue Buster to battle Dumbbellloid with a feat of strength before destroying him.
By that time, after Stag Buster frees the others, Beet Buster reveals that he was joking to Gorisaki earlier, as Red Buster and Yellow Buster relay this new bit of information to Ryuji. By then, the Dumbbellzord arrives with Buster Hercules formed to back up the GT-02 Gorilla as it sends the Vaglass Megazord flying. With the enemy dealt with, Blue Buster uses the GT-02 Gorilla to attack Buster Hercules for the trouble Masato put him through.
Later, as Ryuji gets Masato and Jay in a double headlock, Hiromu and Yoko are glad their friend is all right.
- Hiromu Sakurada (桜田 ヒロム Sakurada Hiromu): Katsuhiro Suzuki (鈴木 勝大 Suzuki Katsuhiro)
- Ryuji Iwasaki (岩崎 リュウジ Iwasaki Ryūji): Ryoma Baba (馬場 良馬 Baba Ryōma)
- Yoko Usami (宇佐見 ヨーコ Usami Yōko): Arisa Komiya (小宮 有紗 Komiya Arisa)
- Masato Jin (陣 マサト Jin Masato): Hiroya Matsumoto (松本 寛也 Matsumoto Hiroya)
- Cheeda Nick (チダ・ニック Chida Nikku, Voice): Keiji Fujiwara (藤原 啓治 Fujiwara Keiji)
- Gorisaki Banana (ゴリサキ・バナナ Banana Gorisaki, Voice): Tesshō Genda (玄田 哲章 Genda Tesshō)
- Usada Lettuce (ウサダ・レタス Usada Retasu, Voice): Tatsuhisa Suzuki (鈴木 達央 Suzuki Tatsuhisa)
- Beet J. Stag (ビート・J・スタッグ Bīto Jei Sutaggu, Voice): Yuuichi Nakamura (中村悠一 Nakamura Yūichi)
- Takeshi Kuroki (黒木 タケシ Kuroki Takeshi): Hideo Sakaki (榊 英雄 Sakaki Hideo)
- Miho Nakamura (仲村 ミホ Nakamura Miho): Fuuka Nishihira (西平 風香 Nishihira Fūka)
- Tooru Morishita (森下 トオル Morishita Tōru): Naoto Takahashi (高橋 直人 Takahashi Naoto)
- Enter (エンター Entā): Syo Jinnai (陳内 将 Jinnai Shō)
- Messiah (メサイア Mesaia, Voice): Seiji Sasaki (佐々木誠二 Sasaki Seiji)
- Dumbbellloid (ダンベルロイド Danberuroido, Voice): Jūrōta Kosugi (小杉 十郎太 Kosugi Jūrōta)
- Civilian: Mayumi Tooda (遠田真弓 Tooda Mayumi), Kanako Fujita (藤田可奈子 Fujita Kanako), Yassi (ヤッシー Yasshī), Mari Konno (今野マリ Konno Mari)
- This episode is the 1800th overall in the Super Sentai Series.
- As part of Super Hero Time, this episode aired alongside Kamen Rider Fourze episode 43, Light and Dark Twins.
- Viewership: 4.8%
- Unlike in some previous episodes, Ryuji's voice in this episode does not sound distorted during his overheated state.
Tokumei Sentai Go-Busters Volume 6 features episodes 21-24: Mission 21: Farewell, Blue Buster, Mission 22: The Beautiful Avatar: Escape, Mission 23: The Will of the Inheritors and Mission 24: A Très Bien Summer Festival. 
- Boxed In (Beast Morphers) - Power Rangers counterpart in Beast Morphers. See comparison page. (fight footage & story)