No documented source, character or release year is supplied with this entry, so its history cannot be traced to a show, game or viral video from the information available. What is clear is its presentation as a short Japanese-titled soundboard clip, a format that circulates when listeners save, share and reuse a title or moment in their edits. The question mark in メルティー列車? gives the entry a meme-like hook, and that curiosity, rather than a known backstory, is what makes it reusable. Creators tend to treat such clips as fragments, borrowing the title to add humor to unrelated footage.