Ophiuca

Ophiuca, known as Ophiuchus (オヒュカス) in Japan, is a manipulative FM-ian based on the serpent-tamer constellation, Ophiuchus. Her form is that of a dark purple Nāga, with the power to control snakes.

Mega Man Star Force
In the game, because of Luna's involvements with numerous FM-ian incidents, caused her parents to transfer her to a new school. She keeps this painful news away from her friends. At the mall, she observes Geo and Sonia while they attend a jungle exhibit, and tailed them out of jealously. There she has an unexpected run-in with her parents, and the confrontation prompts Ophiuca to appear before her. Ophiuca promises to make Luna's parents pay, and Luna allows Ophiuca to invade her heart, merging them together to create Queen Ophiuca. Queen Ophiuca holds Luna's parents hostage demanding Omega-Xis to hand over the Andromeda Key so that they may "use its power together". Mega Man eventually defeats Queen Ophiuca, but she was not finished off since Omega-Xis doesn't go hard on women (like Lyra, whom he also did not finish off.). Gemini appears by voice, while Ophiuca asks him to defeat Omega-Xis, who says the two of them together will be a tough job. However, Gemini kills Ophiuca on a whim.

After being defeated, Cepheus later resurrects Ophiuca and sends her after Mega Man to stop him from approaching Andromeda, but she lost.

Mega Man Star Force 2
Ophiuca does not appear in this game. However, after Hyde kidnaps Luna, he forces the remains of Ophiuca's data to transform Luna into Queen Ophiuca.

Mega Man Star Force 3
Ophiuca does not appear in this game as a boss, but instead, as a Noise Change.

Anime History
In the anime, Luna suspects that Mega Man is unaware of his secret identity. It was because of this weakness that she is targeted by Ophiuca during one of Sonia's concerts, taking advantage of Luna's desire to see her hero and her jealousy over Harp Note, who she believes may be romantically involved with Mega Man. Luna allows Ophiuca to invade her heart, merging to create Queen Ophiuca. Mega Man and Harp Note team up and defeat her. Unfortunately, Ophiuca escapes.

Later, Ophiuca takes on the form of W Luna while gathering minus energy to recreate the Andromeda Key. During this time, Ophiuca often bickered with other FM-ians over how to spend money, and she herself also developed a love of shopping. Eventually, Ophiuca is deleted by Gemini Spark in order to fill the Andromeda Key.

Trivia

 * A noticeable feature between the game and the anime is a minor part in Ophiuca's appearance. In the game, she is displayed holding a flute with both hands (showing a "snake's enchanter" suggested appearance); however, in the anime, the flute is absent. It is unknown if this was a mistake or not.
 * She's the only story related FM-ian who doesn't return in Megaman Starforce 3.