This a Moon melon, scientifically knows as asidus . This fruit grows in some parts of Japan .It is known for its weird blue color. It can switch flavors after you eat it, everything sour will taste sweet, and everything salty will taste bitter and it gives water a strong orange-like taste. I read it from internet only. But some sources said it is a Photoshop effect of red water melon. If anybody know about this please clarify my doubt.