 Japanese title card · “Lost Planet” | |
| Series | Sonic X (ソニックX), TMS Entertainment |
| Season | Season 3 (2005–2006) |
| Episode | Season 3, episode 22 · no. 74 of 78 |
| English title | “Eye Spy” (4Kids) |
| Japanese title | ロスト・プラネット (Rosuto Puranetto, “Lost Planet”) |
| Japan | Not shown on Japanese TV until 24 April 2020 (Kids Station) |
| First aired (US) | 8 April 2006 · 4Kids TV (Fox) |
| Directed by | Hideki Hiroshima |
| Written by | Kiyoko Yoshimura |
| Storyboard | Masanori Mizuhara |
| Previous episode | The Cosmo Conspiracy (S03E21) |
| Next episode | Agent of Mischief (S03E23) |
Metarex SagaCosmo’s secret
Eye Spy is episode 22 of Season 3 of Sonic X and the 74th of the anime’s 78 episodes. In Japan it is called “Lost Planet” (ロスト・プラネット). It premiered in English: 4Kids aired it on 4Kids TV (Fox) on 8 April 2006, after a French TV debut on 14 April 2005, while Japanese TV only showed it on 24 April 2020. It was directed by Hideki Hiroshima and written by Kiyoko Yoshimura.
Synopsis
The flash that ended the last episode drops the Blue Typhoon on a deserted planet, and the truth sinks in: through the girl they call White Seed, the Metarex have seen and heard everything. Shadow’s attack suddenly makes sense. Sonic and Chris, at least, are back on their feet.
Tails and Chris trace the signal to Cosmo’s brain, but it is wired into the part that handles sight and sound, so removing it could leave her blind and deaf; Knuckles wants the operation anyway. Out exploring, Amy runs into Rouge, and the two uncover the planet’s past: it was Cosmo’s homeworld – and the Metarex’s. Long ago some of its people crystallised their Planet Egg to fuel monstrous war forms, then left and became the Metarex.
Horrified, Cosmo wants to leave, but Tails and the others vow to fight on with her, spy signal or not. Shadow turns to go – until Bokkun arrives with news that Eggman has been captured, Dark Oak holds all seven Emeralds, and his “forestation” is about to begin.
Key Moments
- Cosmo is revealed as an unwitting Metarex spy.
- The lost planet turns out to be Cosmo’s homeworld.
- The crew vows to protect Cosmo.
Trivia
- Cosmo’s Metarex codename is White Seed.
- On home video: the So Long, Sonic DVD set (2007); and Discotek’s Sonic X Collection 2 (2016) and complete-series Blu-rays.
Watch the Episode
The full 4Kids English episode, uploaded by TMS Entertainment’s official “Anime! on TMS” YouTube channel (checked 6 November 2026).
Part of our Sonic X Season 3 guide. See the Sonic X series page for the cast, theme songs and home video.
Sources: titles, credits and air dates from Wikipedia’s list of Sonic X episodes and Sonic Wiki Zone, cross-checked with each other and with Luke’s original Sonic Scene episode table; synopsis written for Sonic Scene from the episode, Wikipedia’s summary and Sonic Wiki Zone’s plot notes; title card and screenshots via Sonic Wiki Zone, copied to our media library.