I don't know if this makes more or less sense now that I know it takes place after parts 2 and 3. It almost feels like a pilot chapter, it doesn't really fit into the timeline of the rest of the series.
Reimu*(, I'll ) absolutely win (against you next time.)
*from last page
Fu- is sound effect.
The implication is that Reimu had a slight misunderstanding when hearing Cirno say her name.
...no, no one is nearby...Absolutely...
Win...
Fu-Right... everything that happened todayeverything... is Cirno's fault...Rea, really... sneaky sleep talk...For ever after... you will take responsibility, right?Get ready, my little idiot.