Mikasa was walking next to Eren, heading back towards the HQ.
Eren saw Armin and ditched Mikasa.
Mikasa was sad.
Then, she saw a black notebook on the ground.
She picked it up, and there was a creepy thing next to her.
"What are you?" Mikasa asked, keeping her cool.
"I am a shinigami," it replied.
Mikasa looked at the shinigami.
"This notebook says 'Death Note' on it, does it kill people?" Mikasa questioned the shinigami.
"Only if you write people's names in it," the shinigami responded to her.
Mikasa used the Death Note to kill people who she thought was a threat to Eren.
Which was basically everyone.
Wow Mikasa, wow.