Luna is over the moon at the results of the round - everyone allied! She and Sigma go to the garden and talk about her background. Luna also catches Sigma in a paradox: he says that he met someone in the garden, but at the same time couldn't have been there. Luna also suggests that the white blood coming from Sigma's palm could indicate that he is a robot and has been in the facility for a long period, which would explain his knowledge about the garden. Sigma is surprised that he isn't that shocked by this.
The bombs are discovered in the facility, and Sigma announces that he knows Dio planted the bombs (with a Phoenix Wright reference), although he isn't sure how. The others tackle Dio but accidentally separate the detonator from him, setting the bombs on 30 minute countdown. Everyone panics and goes to look for the codes for the bombs or the password entry device.
Sigma finds Luna in the Infirmary and she says she's been waiting there to scan him with the ADAM. Sigma is surprised by this, but allows her to scan him since she's clearly waiting for him for that reason. The scan reveals that Sigma is not a robot, but he does have cybernetic arms, although Luna can't say how he got them. Sigma and Luna talk briefly, until Luna points out there is only one minute left before the bombs explode. Luna tells Sigma that she was told to tell Sigma to remember something, and Sigma is baffled - how can he remember something when he's about to die? Luna gives the first code for the two-headed lion, and then, as the bombs finally explode, wishes that she'll "see Sigma again, somehow."
On the PS Vita version, getting this ending gives the achievement Arms Race.