Komachi is the grim reaper and is pissed she didn't get her death on time, and is basically tormenting her crush/enemy by showing her the butterfly effect of her actions before reversing time and letting Satsuki make the 'right' choice in order to let everyone else live who have died so far. Satsuki will save her again (worst ending is she dies in her place after spending the day helping Akira and co), and there'll be some big, dramatic faceoff where somehow one of their ideologies is forced to stand down.
If I don't get some kind of an ending like that, I'm going to be so pissed because Seo's shit makes absolutely zero sense, and the story is tailspinning into absolute shitsville now.