"Ochu" comes from Dungeons & Dragons; specifically, it is the otyugh. The name in Japanese (and transliterations) comes from the pronunciation; it is pronounced with a short O and T (practically to a ch), making the pronunciation close to "o-chuugh". "オチュー" is the closest the katakana system can get to representing the sound without using compound katakana pronunciations not natively found in Japanese.
Usage
See Special:Whatlinkshere/Etymology:Ochu for a list of articles using this term.
This is an etymology page: a page detailing the origins of terminology used in the series in regards to real world culture and history.
