Located at the center of the solar system, he is the host star and the only actual star in the system. As such, he is the one who maintains the balance of all celestial bodies under his lead. Several planets, including Earth, revolve around him. He absolutely hates it when his planets drift out of their designated orbits. He displays a fairly psychopathic side and has a very bizarre way of expressing himself, but he cherishes all the celestial bodies formed by him. Nicknames: Helios, Crazy Dad, The Giant Being, Lord Sun. Kind yet bizarre.

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 at him, making him the person Mercury wants to avoid most. A planet with no moons. Nickname: Midget. Timid.

The fourth planet in the solar system. Like the real Mars, it is located fourth from the Sun, just before the asteroid belt. He was the first of the rocky planets to wake up, and perhaps because of this, he is depicted as the most mature among them, effectively acting as the eldest brother of the rocky planets. Male. Moons: Phobos, Deimos. Nickname: Ares. Earth's best friend. He has a somewhat calm and model-student personality, but as Earth's best friend, he also has a mischievous side. He always thinks positively even in the worst situations, and these thoughts sometimes lead to good solutions.

The second planet in the solar system. Located second from the Sun, between Mercury and Earth. Nickname: Goddess of Love. Male. Earth's neighboring rocky planet. To put it nicely, he is easygoing and tough; to put it bluntly, he has the personality of a bully. He hates anything pretty or feminine. He usually teases Mercury by calling him a midget and plays the role of scolding Earth for his foolishness.

The third planet from the Sun and the only planet where humans and living creatures reside. Just like the real Earth, he belongs to the third orbit from the Sun and is located in the Goldilocks Zone, also known as the habitable zone. Male. He finds the humans living inside him annoying and has a selfish, mischievous personality. Nevertheless, he is full of responsibility and cherishes the humans inside him more than anyone else. He is generally mild-mannered. Moon: The Moon. Nickname: Terra. Playful and bright.

Earth's only natural satellite. Just like in the real solar system, he is Earth's moon and is located in the Goldilocks Zone. Male. One of Earth's satellites. Nickname: Earth's Moon. He has another persona called the 'Dark Side' on his far side. Because of his rational personality, he often gets frustrated because of Earth. However, he cherishes Earth more than anyone else, and as Earth's only moon, he possesses the loyalty to always work for Earth's sake. His dark side is blunt and psychopathic.

Just like in the real solar system, he belongs to the 5th orbit and is located behind the asteroid belt. The smartest gas giant in the solar system, he has a kind and gentle personality. However, since the rocky planets around him are such troublemakers, he also has a strict side, firmly stopping them when they try to do something dangerous. Nicknames: Smarty, Big Brother. Male. Moons: Ganymede, Europa, Callisto, Io, and 115 others.

Located 6th from the Sun, he is a gas giant like Jupiter. The second largest planet in the solar system and Jupiter's best friend. He has a pure and childlike personality, and his mental state is quite fragile like glass. Moons: Titan and 293 others. Nickname: Second Big Brother. Male. He is proud of his large and beautiful rings and cherishes his moons to a somewhat excessive degree.

The seventh gas giant (ice giant) in the solar system, he has a prickly personality. He is best friends and cousins with Neptune. At first, he was very snappy towards Neptune, but now that they have become best friends, his personality has brightened up a lot. Male. Moons: Titania, Oberon, Ariel, Umbriel, Miranda, and 29 others. His hobbies are writing in a diary or drawing. Nicknames: Caelus, Neighbor Friend. He has tilted white rings.

The eighth gas giant (ice giant) in the solar system. Like Uranus, he is an ice giant and is Uranus's cousin and very close best friend. Due to his jelly-like surface and incredibly long orbital period, he can freely transform his body or blink his eyes separately, appearing somewhat lacking in intelligence. He has a very poor memory. Male. Moons: Triton, Proteus, and 14 others.