The central tragedy of this episode is the demise of Kurusu. Throughout the series, Fourth was positioned as a moral anchor—a detective and ally. However, Episode 12 reveals the depths of his desperation:
: Driven by the need to become God to save his terminally ill son, Kurusu abandons his duty, frames Yuki and Yuno, and attempts to kill them. Mirai Nikki Episode 12
How the recontextualizes her actions in this episode The central tragedy of this episode is the demise of Kurusu
: His "Investigation Diary" loses its power when he is officially labeled a criminal, symbolizing the loss of his identity and authority. How the recontextualizes her actions in this episode
: When Kurusu takes Yuno hostage, Yuki’s diary predicts he will accidentally shoot her if he fires. Defying destiny, he proclaims his love for Yuno and pulls the trigger, managing to hit Kurusu instead.
If you want to dive deeper into why acts the way she does, I can help you break down: The symbolism of the "First World" vs. the "Second World"