On the preview of the 13th episode of Kamen Rider OOO, aside that we will see another of Kazari's Yummies in action, we saw a glimpse of the Birth Driver inside a suitcase which seems to be Maki's office.
As we all know, the rumor about Maki and Kazari joining forces is confirmed, accordingly, the first user of the Birth System for the film is not Gotou but someone else. Could that someone else be Kazari since there is an info surfaced that Maki is trying to create something for Kazari.For more in-depth focus on the Birth System itself, you can check these previous articles:
This is just a fan speculation. Let's wait for the confirmation coming from TOEI or any official source of information such as scans and the like.