The name of the temporary group that Maki Ohguro and Koji Kikkawa has finally been named! Called Daikichi, which was derived from their respective surnames kanji, Ohguro (大黒) and Kikkawa (吉川) these characters together mean, "excellent luck."
The title of the single the two collaborated is called, HEART∞BREAKER. The single will be released on 15/12 which is 3 days before the premiere of the movie. It will be released in 2 versions, one with a DVD of the PV which costs 1890 yen, there's a possibility of a making-of the PV included in it. However there is no official information about that yet. The second version is a plain old CD with the song for 1260 yen.
Source: CSToys Blog
UPDATE: The preview of the single is now available on YouTube but the embedding function was disabled by the uploader. Along with the preview, an interview with Daikichi is part of it.