Moon melon, scientifically known as asidus.
The moon melon appears to have physical characteristics to that of a watermelon, aside from its bright blue colour. According to several sites online, they all have the same description:
Grown in some areas of Japan, the moon melon is known for its unusual blue colour. The strange thing about this fruit is its odd nature of altering the flavours of other foods after it is consumed. For example, foods with a sour or acidic taste will taste sweet on the palate, and salty foods will take on a bitter characteristic. It is also known to give water an intense orange-like flavour. The fruit itself is quite expensive, costing around ¥16,000 JPY, which amounts to approximately $200 USD.
It is quite obvious that after viewing the image of the so called ‘moon melon’, one can see that it is a doctored image of a watermelon, and that a melon with such claims doesn't exist. The size of the melon, and the similar attributes that it shares with the common watermelon can be seen in the shape of the seeds, texture of the flesh and rind, and the unrealistic intensity of the blue colouring.
However, it is true that Japan's priciest melons are called 'moon melons', admittedly very different to newfangled blue moon melon. They are slightly oval in shape and smallish in size, about the size of a young baby’s head. They are usually given as 'gift melons' in Japan, selling for about $100 USD, because they are greenhouse grown, expensively packaged, and the skin is completely unblemished. The flesh is actually very sweet, the colour white to green as opposed to vibrant blue, and generally weigh 3-4 lbs (1.5 to 2 kilograms).
In California, they can be field grown but nobody seems to bother."
- Andrew Grygus, Clovegarden.com.
While the blue, taste-altering version of the melon does not exist, there are various natural fruits that contain the coveted flavour-enhancing aspect. For example, the synsepalum dulcificum (miracle berry), is known to make sour foods taste sweet.
Undoubtedly, many people would crave for a melon that proclaims to mix up the senses. It would probably contain chemicals that alter the receptors of taste on the palate, some of which might even be dangerous, although seen as a recreational activity. Perhaps if scientists could create a hybrid of a watermelon and a miracle berry, and find a way to colour it blue, the moon melon could be born.
The Mad Weeks of May