Osawa's reaction upon hearing that Mamoru Tanaka is dead. As Tanaka holds the other key to open the lab to retrieve the antiviral for the Ua virus and gaining access to the lab requires at least two people with the key to activate, there was no other plausible way for Osawa to cure Maria of the virus before the symptoms surfaced.
Even worse, Ai reacted less calmly upon hearing the bad news. Given that she loved Tanaka but has to marry Osawa for the sake of her family's pharmaceutical company, it is heartbreaking to see her despairing over him, a far cry from her usual serious demeanor up to this point.
Tateno's backstory of being childhood friends with Achi's parents, Daisuke and Kotone. Kotone was held hostage by a terrorist he was looking for, and despite Daisuke's pleas, Tateno shoots him to try and save Kotone, only to get her killed instead. He spends years later as a Knight in Sour Armor until the morning at the trade-off, Daisuke calls Tateno and pleads him to kill Hitomi. She has a rare blood-type necessary for a heart transplant that can save his daughter Suzune's life, and Tateno, though wary, agrees with this to make up for Kotone.
Achi's realization that his own father was trying to get Hitomi killed to save Suzune.
Achi talking his father out of said plan after getting him to realize how much it would actually hurt Suzune and the two of them reconcile.
When Achi and Kano discover a bomb in the fake Alphard's suitcase and is about to go off, Achi calmly and resolutely hugs the case. He knows he can't get away with his leg injury, but tries to save the city he loves anyway by staying in place and telling everyone to get away. Hitomi almost doesn't let him go through with this and hugs with him to stay, but he pleads her to get to safety. If the wrong choice is made, Kano will try in vain to drag Achi away from the bomb only for both of them, and presumably everyone else at the scramble, to die.
