Another new floor opens up after the successful resolution to the last trial, but this isn't the most pressing concern in Naegi's mind right now as he tries to process what he's just seen.
Although he refuses to talk to Kirigiri about it (much to her chagrin), Naegi is primarily pondering why Oogami is fighting with Monokuma - could it be that she's the previously mooted "mole" in their midst? It doesn't take too long before we find out, as Monokuma himself announces that Sakura is indeed his secret agent, to the dismay of all and the disbelief in particular of Asahina who refuses to believe this role was taken up by her friend out of anything other than duress.
In fact, Asahina's support for her friend is absolute, leading to a major falling out with Togami and a scrap with Genocider as she refuses to back down from her stance. While Naegi and Kirigiri are sidetracked by both revelations about the past of Hope's Peak Academy and Alter Ego's request so that she too can join the battle to escape the premises, another murder is carried out - they target this time is hardly unexpected, which might just make tracking down the culprit much more difficult.
At this point in the series Danganronpa's episode structure is set in stone to ensure no surprises, but I'm still enjoying it in spite of this - this week's episode in particular builds up a pretty compelling locked room murder-mystery for us to get our teeth into (with hopefully a little more time spent on gathering evidence than the rushed montage at the end of the episode), and its character interactions only serve to accentuate said mystery. I'm still waiting for this series to spiral off into outright lunacy to the point where I lose interest, but for now it's doing a good job of staying on the rails, albeit by the skin of its teeth at times.