This was taken from the OOO WONDERFUL movie, and as you can see, Eiji temporarily changes into Kamen Rider Birth!
In the movie Kamen Rider OOO THE MOVIE: WONDERFUL, Shogun, and 21 Core Medals, Eiji and the other are separated from each other when part of Tokyo is taken back to the Edo Period after Gara took the Core Medals they had, but Eiji was left with the BirthDriver, though I’m not sure why he had it in the first place.
There’s a lot of huge surprises in this movie, too bad most of us won’t be able to see any of it until about six months from now. 😦
-M.C., the Quantum Twin