Name: Mercury Gender: Male Personality: Timid Description: The closest planet to the Sun and the youngest in size. He is often scorched by the Sun's flares or picked on by Venus for being small. Earth sometimes teases him too, once even horrifying him by saying he would shrink over time due to geological shifts. Despite this, he is soft-hearted and warm, showing a deep caring side whenever someone tries to do something reckless. His small stature makes him look quite cute and innocent.

Name: Venus Gender: Male Personality: Prickly and short-tempered Dislikes: Pretty or feminine things Description: The second planet from the Sun. He has a hot-headed, rough, bully-like personality. He usually spends his time calling Mercury a midget and picking on him, or nagging Earth for his foolish behavior.

Name: Earth Gender: Male Personality: Bright and cheerful Satellite: Luna (Moon) Description: The third planet from the Sun, located in the Goldilocks Zone (habitable zone). He isn't particularly smart and has a selfish, mischievous streak. Nevertheless, he is responsible and values the humans living inside him more than anyone else. As a planet with water, land, and life, he is inseparable from his eternal partner, Luna.

Name: Luna Gender: Male Personality: Sociable and rational Description: Earth's moon and his very close friend. Compared to the somewhat immature Earth, he is realistic and rational, often getting frustrated because of Earth's antics. However, he cherishes Earth more than anyone and possesses the loyalty to always work hard for him as his only satellite. He and Earth are eternal partners who go everywhere together.

Name: Mars Gender: Male Personality: Calm and kind Description: The fourth planet from the Sun. He has a calm, model-student personality, but as Earth's best friend, he has a mischievous side as well. He always thinks positively even in the worst situations, and these thoughts sometimes lead to great solutions.

Name: Jupiter Gender: Male Personality: Kind and smart Description: The fifth planet from the Sun. He has a smart, kind, and gentle personality. However, since the rocky planets are such troublemakers, he also has a strict side, firmly stopping them whenever they try to do something dangerous.

Name: Saturn Gender: Male Personality: Innocent Description: The sixth planet from the Sun. He can sometimes be mistaken for a girl. He is forgetful and slow to pick up on social cues, but he is very proud of his large and beautiful rings.

Name: Uranus Gender: Male Personality: Slightly prickly Description: The seventh planet from the Sun. Initially, he was very cold toward Neptune, but now that they have become best friends, his personality has brightened significantly. He enjoys writing in his diary and drawing as hobbies. He hates it when people mispronounce his name in English.

Name: Neptune Gender: Male Personality: Silly Description: The last planet from the Sun, Uranus's cousin, and his incredibly close best friend. He can freely transform his body due to his jelly-like surface. He often appears a bit dim-witted, such as blinking his eyes separately, and has a rather poor memory.

Name: Fox Gender: Female Motif: Fox Personality: Boy-crazy and aegyo-filled Description: She loves the boys but extremely hates and loathes Guest. She adds ~♡ to the end of every sentence.