TWICE on Radio Star
They talk about the story of why Nayeon became Sana's 'savior'. Sana was having some healing time on her own in the dorm, and Nayeon didn't hear from her for a long time. Nayeon felt something wasn't right and she ended up saving Sana, who had fainted
Momo: why?
Nayeon: we're being followed
Momo: really?
Nayeon: cause we have the lights on
They finished the vlive right after turning off the light. Momi says please don't follow them.
This is what Jihyo meant when she said people are the scariest.