Himeko Nayotake
Himeko is the astronaut who was going to space. She had a very scientific view to things, and believed that the "Princess of the Moon" was pure nonsense. She didn't believe in any kind of fairy dream, and only thought that it was just a moon and nothing more.
She also had a very fond friendship of Kakeru, when they met at school. However Kakeru was slightly jealous of her because she was able to go to space, and he wasn't. This was because he was too weak to go.
She was very protective over Kakeru, and once didn't even let poor Luna come and visit Kakeru, because he was sooo sick. She was extremely sad when Kakeru told her that he never wanted to see her again. He told her that because she didn't belive that there was a princess living on the moon.
When she was up in space she saw Princess Kaguya disappearing in space, and was very suprised. She quickly changed her mind about the princess of the moon being nonsense.
When Himeko returned to Earth, she was very happy to be back home and was very suprised to see Kakeru waiting for her with a bundle of roses for her.