After that, Midori relates to Akihiro about Keisuke's death. It's made clear that she still recalls it vividly and misses him dearly.
Junpei's death and how he opted to instead give her his persona to stabilize her condition, rather than be brought back.
Chidori's explanation of death to Aegis. Only someone who has experienced it could put it so succulent a tone.
Chidori: "Death is loss, Aigis. Only when you lose something that can never be replaced can you understand death. And only when you hold on to that which will be lost can you understand life."
The argument after the reveal of Frosty not being a standard Persona. Because she gave her word, she can't tell them the truth, which results in confusion and distrust.
The Answer
Minato's death.
The Interlude
Midori paying her Due to the Dead. It's clear that the Lockdown still held a lot of bitter memories for her.
Midori ends up accidentally killing Adachi when he throws them into the television and tries to kill her and Saki. It was self-defense, but given her hangups and the look of horror in her face, it was clear she'd done the one thing she never wanted to.
