The Mewmao is an enemy from Final Fantasy XIII-2. It appears during rainy weather with groups of many other creatures, and since its HP is usually lower than theirs and it is capable of healing them, it should be defeated first. It does not have much in the way of defenses or attacks, so this should not be a difficult task.
Mewmao is commonly used to infuse the Resist Magic +36% ability, but along the way to that is the less-than-perfect HP +25% ability (the maximum is HP +30%). This 25% is relatively common, so if the same coincidental addition of a 25% occurs again, it will become yellow-locked and require a third HP +25% to remove the yellow lock.