Steamboy 2?

According to Anime News Network:

The Steamboy 2 story will focus on main character Rei's further adventures, but there are also plans for an episode of heroin Scarlet becoming "Steamgirl" to be produced as a separate work.

Steamboy producer Watanabe Shigeru said in a speech on July 17th, "I talked with Otomo about what Rei does afterwards and the story of Scarlet becoming a "Steamgirl". We will try to realize this within 2 years. I would also like to see Miss Suzuki and Miss Konishi (voice actors) on board the coming project."

"I hope I will still be able to do a girls voice in two years" said Scarlett's voice actress, Konishi Manami, who is twenty-five.According to Natsume Maya it was stated that the sequel may be another movie, or it may be a TV anime.

According to the official Steamboy website, there will be a manga released in Weekly Young Magazine to commemorate the Steamboy theatrical release. The Manga will be released over three weeks, with this week's installment a 10-page story called "Steam Jiji-san" (Steam Grandfather).