According to a report from Heroic Hollywood, "Man of Steel 2" will introduce audiences to Kara Zor-El aka Supergirl as well as to Bizarro and Brainiac. The film will serve as a sequel to "Man of Steel" — not to be confused with "Batman v Superman: Dawn of Justice," which will serve as an introduction to Batman (Ben Affleck) and the Justice League. 

The report states that the main villain in "Man of Steel 2" will be Brainiac, one of the most intelligent lifeforms in the universe who wants to gain the Kryptonian codex similar to General Zod's (Michael Shannon) goal in "Man of Steel." However, instead of getting the codex from Superman (Henry Cavill) body, he will try to steal a copy from Kara Zor-El. 

In the "Man of Steel" prequel comic, it is revealed that Kara arrived on Earth thousands of years before Superman did, and it is possible she is still alive, also in hiding. When Brainiac comes to Earth hunting for her, she may have to reveal herself to her relative Superman in order to fight back. 

Heroic Hollywood also reports that Brainiac will use the little Kryptonian information he has to create the villain Bizarro. In the comic books, Bizarro is akin to a corrupted version of Superman, with a twisted mind and knack for violence while still possessing the same strength and speed of a Kryptonian on Earth.

It is possible that Bizarro will be Brainiac's agent sent to Earth to hunt down and fight both Supergirl and Superman.

According to the report, this was the original pitch for "Man of Steel 2" that director Zack Snyder and David Goyer presented to Warner Bros. executives. The focus on a strong female lead is also reportedly what attracted director George Miller to the project, who is most recently known for directing "Mad Max: Fury Road." 

However, the story should still be taken with a grain of salt as there is no official confirmation from Warner Bros. Pictures at the moment.