 Japanese title card · “Summer Vacation Diary – Chao Observation” | |
| Series | Sonic X (ソニックX), TMS Entertainment |
| Season | Season 1 (2003–2004) |
| Episode | Season 1, episode 22 · no. 22 of 78 |
| English title | “Little Chao Lost” (4Kids) |
| Japanese title | 夏休み・チャオ〜な観察日記 (Natsuyasumi Chao~na Kansatsu Nikki, “Summer Vacation Diary – Chao Observation”) |
| First aired (Japan) | 31 August 2003 · TV Tokyo |
| First aired (US) | 28 February 2004 · Fox Box (Fox) |
| Directed by | Masafumi Satō |
| Written by | Kiyoko Yoshimura |
| Storyboard | Kōichi Sasaki |
| Previous episode | Fast Friends (S01E21) |
| Next episode | Emerald Anniversary (S01E23) |
Summer holidayChao
Little Chao Lost is episode 22 of Season 1 of Sonic X and the 22nd of the anime’s 78 episodes. In Japan it is called “Summer Vacation Diary – Chao Observation” (夏休み・チャオ〜な観察日記). It premiered on TV Tokyo on 31 August 2003, and the 4Kids English version followed on Fox Box (Fox) on 28 February 2004. It was directed by Masafumi Satō and written by Kiyoko Yoshimura.
Synopsis
It’s summer, and the gang heads for a valley in Japan where Mr. Tanaka spent his youth. Chris, Danny, Frances, Mr. Stewart and the animals go camping, while Sonic would rather see the sights in town. At the campsite there is cooking and bug-catching – until Cheese, out for a swim, is swept away by the current.
The search that follows leads to a secret: a hidden colony of wild Chao, living around a lake that has to stay clean. Unluckily, Eggman is hiking in the same hills, and when his heavy robot Da-Dai-Oh sinks into the soft ground, the mud it churns up pours into the Chao’s water.
Sonic, wandering back with a bag of souvenirs and enjoying his fame, runs into the villains, who insist they are on holiday. He wrecks the robot and sends them flying, then finds the children trying to strain the mud out by hand and uses his speed to clear the water for them. Around the campfire, Mr. Tanaka admits he found the Chao colony himself as a boy.
Key Moments
- A colony of wild Chao is discovered on Earth.
- Mr. Tanaka takes the gang to his home town in Japan.
- Sonic saves the Chao habitat by running rings around the lake.
Trivia
- Chao, the virtual pets of Sonic Adventure (1998), get a starring role.
- On home video: Japanese DVD/VHS volume 6 (Victor Entertainment, 17 December 2003); 4Kids/FUNimation volume 6, Countdown to Chaos (12 April 2005); the Chaos Emerald Chaos DVD set (2008); and Discotek’s Sonic X Collection 1 (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 1 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.