The info above for this oneshot says it was adapted from D.Gray-man, but that isn't true. It just has some concepts and one character in common - and in any case, it pre-dates D.Gray-man.
Before the author wrote D.Gray-man, she created two different one-shot manga. Info on Wikipedia explains that because Continue wasn't popular, Hoshino's publisher recommended that she create a manga series based on Zone instead. That series became D.Gray-man.