|This article is about a/an episode in Juken Sentai Gekiranger.|
Eighteenth Lesson - Shakkin-Kīn! The Body is Strong (修行その18 シャッキンキーン！身体、強い Shugyō Sono Jūhachi: Shakkin-Kīn! Karada, Tsuyoi) is the eighteenth episode of Juken Sentai Gekiranger. It is the conclusion of the two-part training of Jan by Master Sharkie Chan, while also delving deeper into Rio's past.
Seeing the failures of his style against Dokariya, Sharkie decides to abandon teaching Jan as he doubts his effectiveness as a Geki Juken master.
It is revealed that Geki Shark is possessed by Dokariya, and it takes an attack from Bat Li and Elehung to tell the Gekirangers to use Geki ElephanTohja to defeat Geki Shark for the time being. The two Kensei berate Sharkie, because they feel that he was not up to the task of teaching a student due to his ideals of a strong body being foolish, before Xia Fu arrived and suggested that they all go back to the group's campsite to try and continue the training. Sharkie tries to impress Elehung and Bat Li, but they further scold Sharkie's ideals, and he leaves, disheartened as he renounces Jyan as his student out of failing him. That night, someone uses one of Sharkie's swords to attack Xia Fu, and Miki assumes that it must be Sharkie, with Bat Li, Elehung, and the Gekirangers pursuing him. The next morning, the two Kensei, Retu, and Ran find/capture Sharkie, while Miki and Xia Fu clean up the campsite. While Xia Fu is distracted, Miki picks up one of tent's pins and charges at him, only to be stopped by Jyan who knew something was wrong all along. Dokariya reveals himself after being defeated in Miki's body by Xia Fu and then jumps into Jyan to use him to kill Xia Fu as Rageku wished. However, Jyan overpowers the Hermit Crab-Ken user and forces him out of his body, revealing that Sharkie's training allowed him to overcome the Ringi. Jyan then uses the techniques Sharkie taught him to defeat Dokariya with the Geki Waza Wave-Wave Slash. Dokariya then enlarges and jumps into the sea. But Geki Tohja follows by summoning Geki Shark and combine to form Geki SharkTohja. The battle underwater ends with Geki SharkTohja's Great Firm-Firm Slash destroying Dokariya. After the battle, Xia Fu approves of Sharkie as a true master, bringing the Kensei to tears. Back at the Rin Jū Hall, Rio reveals his one true rival to Rageku: a man with a "White Tiger" Geki named Byakko.
- Jan Kandou (漢堂 ジャン Kandō Jan): Hiroki Suzuki (鈴木 裕樹 Suzuki Hiroki)
- Ran Uzaki (宇崎 ラン Uzaki Ran): Mina Fukui (福井 未菜 Fukui Mina)
- Retsu Fukami (深見 レツ Fukami Retsu): Manpei Takagi (高木 万平 Takagi Manpei)
- Master Sha-Fu (マスター・シャーフー Masutā Shā Fū, Voice): Ichirō Nagai (永井 一郎 Nagai Ichirō)
- Miki Masaki (真咲 美希 Masaki Miki): Kazue Itoh (伊藤 かずえ Itō Kazue)
- Elehung Kam Po (エレハン・キンポー Erehan Kinpō, Voice): Yū Mizushima (水島 裕 Mizushima Yū)
- Bat Li (バット・リー Batto Rī, Voice): Shūichi Ikeda (池田 秀一 Ikeda Shūichi)
- Sharkie Chan (シャッキー・チェン Shakkī Chen, Voice): Hiroya Ishimaru (石丸 博也 Ishimaru Hiroya)
- Rio (理央 Rio): Hirofumi Araki (荒木 宏文 Araki Hirofumi)
- Mele (メレ Mere): Yuka Hirata (平田 裕香 Hirata Yuka)
- Bae (バエ Voice): Akira Ishida (石田 彰 Ishida Akira)
- Sea Fist Demon Rageku (海の拳魔ラゲク Umi no Kenma Rageku, Voice): Naoko Kouda (幸田 直子 Kōda Naoko)
- As part of Super Hero Time, this episode aired alongside Kamen Rider Den-O episode 21, Fighting Style
- Viewership: 5.9%
- Pre-Credits: GekiSharkTohja
- This is the first reference to the 'White Tiger Man' who Rio confessed that is the one person who he feels jelously against
Juken Sentai Gekiranger Volume 5 features episodes 17-20: Lesson 17: Goro-Goro! Teacher and Student Love, Lesson 18: Shakkin-Kīn! The Body is Strong, Lesson 19: Gokin-Gokin! Showdown with Rio, and Lesson 20: Gicho-Gicho! Triangle Opposing Fight.