Mio Kuroki

Mio Kuroki is an character who appears only in Pretty Guardian Sailor Moon. She appears as an idol who gains over-night popularity and becomes the rival to Minako Aino, when the truth was the she was actually the "shadow" of Queen Beryl sent to Earth to spy on the Sailor Senshi. She later reappears in the Special Act as the main antagonist. This is an exclusive character who only appears in Pretty Guardian Sailor Moon.

Biography
In Act 29, she transferred to Usagi's class, and became very popular with all of the students. Since Mio is a rival idol to Minako Aino, Usagi has mixed feelings about her. She hates Usagi, and tortures her repeatedly in devious ways that seem like accidents. Mio has a personal hatred for Minako and consistently tries to upstage her with mixed to failed results.

However, Minako isn't fooled by Mio and understands that she is working for Beryl as an agent for the Dark Kingdom. Her uncaring nature and tormenting of Usagi gave her away to Minako. Naru has also seen past Mio's so-called kindness and is also suspicious of her. Minako wisely has warned Usagi several times to stay away from her, knowing what Mio is capable of, but her kind heart takes over and she forgives Mio, much to Minako's dismay. She cunningly takes advantage of it, believing that she wants to be friends with her. Later, when Mio puts a spell on Mamoru, it is revealed that she is a shadow of Queen Beryl, and that whatever Mio sees or feels, Beryl will also see and feel. Eventually, her uncaring nature in repeatedly torturing Usagi exposes her to Rei. She tells Mio that she knows what she's doing to her friend and will tell her unless she see Mamoru. She allows Rei to see him and she tells him that Usagi is thinking positive. She tries to convince Mamoru to not think about their past lives because she hasn't. Amused by this, Mio reminds Rei that she can't avoid a repeat of what Princess Serenity did in the past when she destroyed the Earth and this time Beryl will make sure that it won't be repeated.

Toward the end of the series, Mio's cruel mistreatment towards both Usagi and Mamoru comes back to haunt her. She is apparently killed by Metaria Endymion for her insolence.

Special Act
She is somehow resurrected as the main villain of the "Special Act". Once again, she kidnaps Mamoru, this time wanting to marry him so they can rule a new Dark Kingdom as King and Queen. She is confronted and attacked by the Shitennou, forcing her to transform into a plant-like youma that makes quick work of her former allies. Ultimately, her final form is destroyed by the Senshi's combined powers, channeled through the Moonlight Stick in the Sailor Planet Attack.

After her revival for the Special Act, she seems to gain new powers. She can repair objects, cause them to appear out of thin air, and create monsters from flames. She can also summon legions of pierrot, or clowns, to serve her and gather energy, even creating replicas of the Shitennou. Mio is also able to brainwash others and transform into a plant-like youma. At one point, she interrupts a television broadcast to announce that she is taking over. Mio immediately incapitates Rei first so she can't warn the others about her plans.

Etymology
The kanji of her surname "Kuroki" (黒木), reads as "black wood."

Mio's name is given in katakana. "Mio" written in kanji has the character for "beauty" (美). Proceeding it can be either the kanji for "cherry blossom" (桜, ou) or "thread" (緒,o).

Trivia

 * The kanji of her surname is the same as Marina Kuroki, the fourth Sailor Moon actress in the musicals.