Usagi fights using the identity of Sailor Moon, and as the story progresses she learns more and more about the enemies which face her and the evil force that is sending them. Gradually she discovers the truth about her own past life, her destined true love, and the possibilities for the future of the Solar System.

The plot spans five major story arcs, each of them represented in both the manga and anime, usually under different names:

1. the Dark Kingdom arc (Sailor Moon)
2. the Black Moon arc (Sailor Moon R)
3. the Infinity arc (Sailor Moon S)
4. the Dream arc (Sailor Moon SuperS)
5. the Stars arc (Sailor Stars)

Usagi Tsukino (月野 うさぎ ,Tsukino Usagi)

The main character of the series, called Serena in the English anime (nicknamed Bunny in the English manga). Usagi, a carefree schoolgirl with an enormous capacity for love, transforms into the heroine called Sailor Moon. At the beginning of the series she is portrayed as an immature crybaby who hates having to fight evil and wants nothing more than to be a normal girl. As she progresses, however, she embraces the chance to use her power to protect those she cares about.

Mamoru Chiba (地場 衛 ,Chiba Mamoru)

A student somewhat older than Usagi, called Darien in the English adaptations of the series. As a young child he experienced a terrible car accident that robbed him of his parents and of his knowledge of who he is. During the series he has some precognitive ability, including dreams that inspire him to take on the guise of Tuxedo Mask and fight alongside the Sailor Senshi. After an initially confrontational relationship, he and Usagi remember their past lives together and fall in love again.

Ami Mizuno (水野 亜美 ,Mizuno Ami)

A quiet bookworm in Usagi's class, called Amy in the English adaptations of the series. Highly intelligent, with a rumored IQ of 300, she can transform into Sailor Mercury, acquiring power over all phases of water. Ami's shy exterior masks a passion for knowledge and for taking care of the people around her. She hopes to become a doctor one day, like her mother, and tends to be the practical one in the group. Secretly, she is also a fan of pop culture and romance novels, and becomes embarrassed whenever this is pointed out.

Rei Hino (火野 レイ ,Hino Rei)

An elegant miko (shrine maiden), called Raye in the English versions. Because of her work as a Shinto priestess, Rei can sense and dispel evil even in civilian form. When she transforms into Sailor Mars she can also manipulate fire. She is very serious and focused, but although easily annoyed by Usagi's flightiness, cares about her very much. Rei is portrayed as boy-crazy in the early anime, but is uninterested in romance in both the manga and live-action series. She attends a private Catholic school, separate from the other girls.

Makoto Kino (木野 まこと ,Kino Makoto)

A tomboy who transfers into Usagi's school, called Lita in the English versions. Very tall and strong for a Japanese schoolgirl, she can transform into Sailor Jupiter, attacking with lightning and with some control over plants. Both Makoto's parents died in a plane crash years ago, so she lives alone and takes care of herself. She cultivates her physical strength as well as more domestic interests, including housekeeping, cooking, and gardening. She wants to marry young and to own a flower-and-cake shop.

Minako Aino (愛野 美奈子 ,Aino Minako)

A perky dreamer who acted on her own as Sailor V for some time. Called Mina in the English versions, she has a companion cat called Artemis who works alongside Luna in guiding the Sailor Senshi. Minako transforms into Sailor Venus, Soldier of Love, and leads Sailor Moon's four inner guardians. She also dreams of becoming a famous singer and idol and attends auditions whenever she can. At the start of the live-action series, she is already these things, but has poor health and separates herself from the other Senshi.

Chibiusa (ちびうさ)

The future daughter of Usagi and Mamoru, Chibiusa travels from the 30th century to seek help to save her parents, then later to train with Sailor Moon to become a soldier. She learns to transform into Sailor Chibi Moon. At times she has an adversarial relationship with her mother in the 20th century, as she considers herself more mature than Usagi, but as the series progresses they develop a deep bond. Chibiusa wants to grow up to become a lady like her mother. In the English adaptations, she is called Rini, and her alter ego is called Sailor Mini Moon.

Setsuna Meioh (冥王 せつな ,Meiō Setsuna)

A mysterious woman, called Trista in the English anime. She appears first as Sailor Pluto, the Guardian of Time, who has the task of protecting the Space-Time Door from unauthorized travelers. It is only later that she appears on Earth, living as a college student. She has a distant personality and can be very stern, but can also be quite friendly and helps the younger Sailor Senshi when she can. After so long at the gate of time she carries a deep sense of loneliness, although she is close friends with Chibiusa.

Michiru Kaioh (海王 みちる ,Kaiō Michiru)

A talented violinist with some precognition, called Michelle in the English anime. A year older than most of the other Sailor Senshi, she can transform into Sailor Neptune, channeling the power of the ocean. She worked alone for some time before finding her partner, Sailor Uranus, with whom she fell in love. Michiru is elegant and personable, already well-known for her music as well as her painting, but has given up her own dreams for the life of a Senshi. She is fully devoted to this duty and willing to make any sacrifice for it.

Haruka Tenoh (天王 はるか ,Ten'ō Haruka)

A good-natured, masculine-acting girl, called Amara in the English anime. Haruka, of an age with her partner, Michiru, transforms into Sailor Uranus, Soldier of the Sky. Before becoming a Sailor Senshi, she dreamt of being a racer, and is skilled at driving. She tends to dress and, in the anime, speak like a man. She is so friendly and genial that nearly everyone she meets is attracted to her. When it comes to fighting the enemy, however, she distrusts outside help and prefers to work solely with Sailor Neptune and, later, Pluto and Saturn.

Hotaru Tomoe (土萠 ほたる ,Tomoe Hotaru)

A sweet, lonely young girl whose name remains unchanged in English (though pronounced slightly differently). Daughter of a possessed mad scientist, she is sickly and weak as the result of a terrible lab accident in her youth. After overcoming the darkness that has surrounded her family, she is able to become the Soldier of Silence, Sailor Saturn. She wields forces of destruction so powerful that she is rarely called upon to use them, and unlike the others, her Senshi and civilian personae seem somewhat disconnected. She is often pensive, and as a human has the inexplicable power to heal others.

-- From Wikipedia