Big brain move from Yuuki.
Werewolves win if they manage to lynch Ayaka the fox and kill one more villager. But if Yuuki is lynched, the unknown werewolf has to kill the fox and try to get one of the other villagers lynched to win.
The villagers can only win if they lynch a werewolf, the surviving werewolf kills the fox, and they lynch that extra werewolf. But they don't even know there's another werewolf bc of what Yuuki said, so they can't vote for Yuuki if they believe the fox is still alive.
If a villager is mistakenly lynched then the fox wins because there will be two werewolves and two villagers. The odds are with Ayaka lol. Too much guessing has to be done on the villagers' and werewolves' side.