Who made Nyan Neko girls?

Can you shed some light on the origin of the popular Nyan Neko girls? Who is the creator behind these charming and visually striking characters that have captured the hearts of so many fans worldwide? Was it an individual artist, a collaborative effort, or perhaps a team working under a particular studio or publisher? And how did the concept of Nyan Neko girls first come to fruition, evolving into the beloved figures they are today?