User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-1758220-20140623215019/@comment-6050823-20140624213831

The Red/Crimson Diablos is canon to the series actually though has never appeared in game sadly. Its unknown if it is a mutation, an extremely angry Diablos covered with blood from it's victims, or something completely different. It could appear later in the series as a special variant in G-Rank or an Event Quest though the armor only found in MHP2nd G actually was also based on it.