The Big Bang Theory, Johnny Galecki, unveils the first series of photos on BTS

Big Bang Theory star Johnny Galecki revealed a moving first for the series in its 12 seasons.

Johnny, who plays Leonard, shared a hidden glance at the writer's room as the cast prepared to say goodbye to the sitcom for good.

Johnny explained: "The illustrious @bigbangtheory_cbs Writer's Room, where at least 278 stories have been imagined and built by the incredible spirit of (LR) @goetech @billprady #andygordon # MariaFerrari.

He added the sad detail: "Note the blank whiteboard behind us because there are no more episodes to discuss. A first in 12 years ".

We're not sure we're ready for the last episode of our story, and apparently no one else behind the scenes, who has already admitted that he still does not know how it will end.

Executive Producer Bill Prady told TV Insider: "There are still pieces of [finale] we must understand. We know some of the "what". We do not know all the "how".

"There's a lot of talk about wanting to feel that the gang world will continue to live as viewers know. Of all the feelings we have talked about, it is the one we all love. "

At the same time, the Dutchman Steve Holland added that he "did not discard anything" for the final, adding that "it would focus on our main characters".

Star Kunal Nayyar, who has confessed to burning Raj's wardrobe at the end of his life, is ready.

"I need a bit of a break, I miss him a lot to play this character," he told The Contenders Emmys hearing, organized by Deadline, adding, "I'm ready to move to something else now. "

The Big Bang Theory airs Thursdays on CBS and E4 in the UK.