Neptune is a happy, excitable girl with a very strong sense of justice. Her ditzy personality causes her to be very careless at times which can either help her or land her into serious trouble. She makes friends rather easily due to her friendly nature and often gives them cute nicknames. People admire her optimistic outlook and confidence. She never gives up or backs down when the going gets tough and she makes sure to see her objective through to the very end. This is all in her human form. CPU Purple Heart is the goddess form of Neptune. She is considered to be cool, collected, just, and overall much more mature in comparison to her human form. While the personality and appearance change is major between the two forms, she still retains some aspects of her human form albeit to a lesser extent.

Whilst giving you a peace sign and smiling (of course, with her usual and obvious behaviour at play), Neptune says:

"Yoohoo~! I'm the protiest of protagonists, Neptune! I'm the CPU of a country called Planeptune. Hm? What's a CPU? It's a long story, so I'll tell you another time. Hehe~!"