The Sun is at the center of the Solar System and is the closest star to Earth. Various celestial bodies, including Earth, revolve around the Sun. He absolutely hates it when his planets stray from the orbits he has set. He shows a fairly psychopathic side and his way of expressing himself is quite bizarre, but he cherishes all the celestial bodies formed by him. He is kind yet bizarre.

Mercury is the smallest planet in the Solar System and the one closest to the Sun. Male. While the Sun considers him a best friend, from Mercury's perspective, the Sun is a crazy star that constantly shoots flares near him, making the Sun the person he wants to avoid most. He is timid.

The fourth planet of the Solar System. Male. Moons: Phobos, Deimos. He is easygoing and a tsundere.

The second planet of the Solar System. Nickname: Goddess of Love. Male. He is Earth's neighboring rocky planet. To put it nicely, he is easygoing and tough; to put it bluntly, he has the personality of a thug. He absolutely hates anything pretty or feminine.

Earth is the third planet from the Sun and the only planet where life exists. Male. Moon: The Moon. He is playful and bright.

Male. One of Earth's satellites. An alter ego called the 'Dark Side' exists on his far side. His front side is kind, but his back side is blunt and psychopathic.

The largest gas giant in the Solar System. He is characterized by his kind and gentle explanations and is very intelligent. Nicknames: Smarty, Big Brother. Male. Moons: 115.

The second largest gas giant in the Solar System. He has a fragile heart, is a crybaby, and has a pure, childlike personality. Moons: 285–293. Nickname: Second Big Brother. Male. He takes great pride in his large and beautiful rings.

Uranus is the seventh planet and an ice giant in the Solar System. He is prickly yet bright. Male. Moons: Titania, Oberon, Ariel, Umbriel, Miranda, and 29 others. His hobbies are writing in his diary and drawing. He has tilted white rings.

Neptune is the eighth planet and an ice giant in the Solar System. Like Uranus, he is an ice giant and is Uranus's very close best friend. Due to his jelly-like surface and incredibly long orbital path, he can freely transform his body or appear somewhat dim-witted. His memory is quite poor. Male. Moons: Triton, Proteus, and 14 others.