In the manga, the Three (Tri-)Lights are an all-female trio who pose as male idol singers, but in the anime Sailor Stars they actually gained the bodies of males in their Earth forms, becoming women again in their Sailor Senshi forms. Their male forms are a disguise as stated by Kakyuu when she asks Seiya if he uses that appearance on Earth. Seiya acknowledges this is true.Towards the end of Sailor Stars, Seiya tells Usagi, "I wanted to tell you my feelings because Seiya's time is short" indicating further that the form taken is a physical disguise. Before coming to Earth, the three Starlights served as protectors of Princess Kakyuu on Kinmoku. The musicals state Kinmoku is located in a solar system called the Galaxy System.They state in Kakyuu-Ouhi Kourin they are from somewhere in Sagittarius. Neither the anime or manga provide specific details of Kinmoku's location. According to Seiya in the anime, who explains their history to Usagi via musical telepathy, Sailor Galaxia attacked Kinmoku in force, with her Sailor Animamates creating an army of phage that swept over the planet.Sailor Star Fighter reveals that, without Kakyuu, the only way the Starlights had of protecting themselves was to kill the phage outright, which also kills the humans they were created from. Because of this, the Sailor Starlights initially go after phage on Earth with a killing intent. They are later dissuaded from this course after Eternal Sailor Moon demonstrates her ability to restore the phage to their human selves. After Princess Kakyuu left Kinmoku to escape Galaxia's assault, Sailor Star Fighter, Star Healer, and Star Maker abandoned the planet to find her. No one else survived Sailor Galaxia's onslaught. The Starlights make references to the comrades they left behind in battle, possibly implying other Senshi who lost their lives on Kinmoku. The three also bring up their family and friends; however, the anime does not reveal any details on the three Senshi's Kinmoku families. The guilt of being the only survivors, of having lived by running away, and the search for redemption by saving their planet serve as the underlying themes for the Starlights through the course of the anime. After escaping from Kinmoku, the Starlights were able to track Kakyuu to Earth and then Japan. The Starlights took male civilian forms - Seiya, Taiki, and Yaten - and became idol singers. They did this to attract as much attention as possible. Their music is embedded with a telepathic broadcast that the Princess (and later Usagi and Michiru) can feel, serving as a beacon to guide Kakyuu to them. By the start of the Sailor Stars anime, the Starlights, now the Three Lights, have become major celebrities across the country. All four of the Guardian Senshi have at some point joined their fanclub, with Ami Mizuno being the first to discover the band (she's member #25). Only Usagi is unaware of them. Several episodes feature the Three Lights having to deal with fans. Later, the Three Lights all attend Jūban High School. As humans, they're all very popular with the Juban students. As Starlights, they distance themselves from the other Senshi, deeming Earth as not being their responsibility. They come into conflict with the Outer Senshi on multiple occasions, as the Outer Senshi view them as invaders. The two groups only reconcile after Uranus and Neptune are mortally wounded by Galaxia, when Uranus charges Star Fighter with protecting Sailor Moon and then dies alongside Neptune.The Starlights prove to be very resilient and exceptionally powerful, surviving multiple direct battles with Galaxia herself. In all, they clash with Galaxia three times: once soon after Kakyuu's death in which they are saved by Chibichibi; again after the deaths of Uranus and Neptune; and a third time to defend Eternal Sailor Moon, in which they become pure energy to battle Galaxia across space itself. Apart from Sailor Moon, they are the only other beings in the galaxy to survive all the way through to the end.
Kou Seiya (星野 光 Seiya Kō?) is the leader of the Sailor Starlights and the lead vocals for the Three Lights. In general, Seiya acts arrogant and tends to be, at least on the surface, confident in his/her own abilities. In the manga, Seiya beats Haruka Tenoh, the physically strongest of the Scouts (and most possible an equal match to Makoto Kino/ Sailor Jupiter), in American football and raises the suspicions of the Sailor Soldiers as to her identity. She also develops deep feelings for Serena, kissing her and thinking as she walks away, "We are of different stations in the universe. It might be unrequited love." In the anime, Taiki and Yaten consider him prone to bouts of childishness (such as when he shows off his basketball skills in front of the school), but generally follow his lead. He hates losing, giving up, or being told he's not good enough. He also behaves arrogantly, saying once, "Usually girls are happy when they see me." ("Why?" Serena asks. "Because I'm cool," he says.) Over the course of the series, Seiya develops strong feelings for Usagi and his attempts to forge a bond with her provides the primary romantic tension of the season. From their first meeting on, Seiya calls Serena Meatball Head, like Darien does. The two even go on a date at an amusement park, which prematurely ends when Sailor Iron Mouse attacks.Seiya makes his interest in her clear when they spend time together practicing softball, telling her, "I like your light." However, Seiya's feelings are not fully reciprocated and acknowledges the one-sided romance, finally kissing her cheek and saying "I wish I had met you sooner." After Galaxia's defeat, before leaving earth, Usagi tells her that they will always be friends. The relationship between Sailor Star Fighter and Princess Kakyuu is slightly ambiguous. In the manga, the princess had a lover who was killed by Galaxia. In the anime, it is implied Seiya's romantic feelings for Usagi may be a confusion with similar feelings for Kakyuu—when he daydreams of his home planet, he thinks lovingly of an image of his princess, which is suddenly superimposed by an image of Serena (much as Serena had seen Seiya's image overlaid by Mamoru in previous episodes). In the image poem released for his CD single, however, he suggests that his feelings for her are because he is "carrying the heart of a boy." Seiya's responsibilities in the band are lead vocals, keyboards, lyrics, and composition. S/he was seen in the anime playing the drums very angrily in their hideout because they think their princess has not heard them yet. After this, Seiya is not seen on the drums again. S/he also enjoys American football and belongs to the club at school. Other "likes" include hamburgers and Physical Education. S/he has trouble with girls and with Literature class, and has blood type A. Seiya is meant to give the impression of a combination of Haruka and Mamoru, and was modelled after Jenny Shimizu.
Kou Taiki (大気 光 Taiki Kō?) is the most intellectual. His/Her abilities rival that of Ami Mizuno (see below), though s/he considers her romantic notions foolish. In the anime, Ami's appeal for him to see the good in dreaming does begin to have an effect, however. In combat with a phage, Star Maker is the first of the Starlights to willingly allow Sailor Moon to heal the monster rather than trying to kill it herself. She spares the monster only because it had been a teacher who Ami respected.Later in the series, as he is beginning to lose hope in finding Princess Kakyuu, he visits a sick girl in the hospital. She shows him a drawing of the Princess that she sees when she listens to the Three Lights play. With renewed hope, Taiki returns to the Three Lights. In the anime, he sometimes wears glasses. Like Yaten, Taiki believes that Seiya should stay away from Usagi after learning she is Sailor Moon, despite their wish, shared by Princess Kakyuu and the Guardian Senshi, for them all to work together. However, his views on Usagi change for the better near the end of Sailor Stars. Taiki's responsibilities in the band are background vocals, keyboards, lyrics, and guitar. S/he also enjoys poetry and belongs to the Literary club at school. Other "likes" include sushi and every class at school, especially Literature. S/he has trouble with arguments, and has blood type AB. Taiki is meant to be more distant than Setsuna.
Kou Yaten (夜天 光 Yaten Kō?) is often distant and cynical about everything. Yaten does not like to socialize or do sports. His/her remarks are often sharp-edged and blunt, which further separates him/her from the world. At one point, the other Starlights even chastise Yaten for behaving in a way that might reduce the number of fans. However, he and Luna get along well. At one point during episode 178, Luna inspires Yaten to keep on fighting. In the course of the season Yaten bonds with Minako Aino who takes a liking to him. Their intricate relationship becomes evident in episode 192 where Minako enters an idol audition and Yaten is one of the jurors. In the manga, Yaten is a female that dresses up as a male. Blunt, and to the point, for example antagonizing Michiru Kaioh for her choice of lipstick. Yaten doesn't interact with the people around her much. She wants to focus on the mission most of all. She is egotistical and nurses grudges, and she hates injury. In the anime, s/he has the most spiritual awareness of the Starlights, and is able to tell when Starseeds are taken by Sailor Galaxia. He views humans as untrustworthy and wants to find Princess Kakyuu so they can leave Earth as quickly as possible. This comes further to light when they discover that Usagi is Sailor Moon. Yaten believes that Seiya should stay away from Usagi, despite their wish, shared by Princess Kakyuu and the Guardian Senshi, for them all to work together. His view is shared by Taiki as well as Sailors Uranus and Neptune. However, also like Taiki, his views on Usagi change for the better near the end of Sailor Stars. Yaten's responsibilities in the band are background vocals, keyboards, and song arrangement. S/he also enjoys photography, but doesn't belong to any school club, preferring to just go home. Other "likes" include caviar and Art class. S/he has trouble with physical exertion and (by extension) Physical Education, and has blood type B.