No cooldown but massive stamina drain. She can rewind time, but she gets more and more tired. Neither The World nor King Crimson drained their users that much, they just had minor limitations.
I’m still waiting for the MC to have some use on the battlefield beyond being a tool lol. I never really noticed it until now, but all of the characters are useful except for him. His only use in the story is as a tool to give us fan service from the girls.
@YukariTakeba What? I was expressing my opinion that time manipulation abilities (mostly the reversal of time, but to a lesser extent, the stopping of time for a non-negligible amount of time) in manga such as these are pretty much always a bad idea, they make it so that most situations have absolutely no stakes and therefore no tension, and the writers have to write their way past a time manipulation ability to keep the stakes high, as the readers might just think "why didn't they just use their time manipulation ability in this situation?". Of course as with everything, good writing can compensate for almost anything.
I just have a feeling the sister is going to die, not from the agency, just from some outside factor. In all honesty, if it were the case, it would make the story a lot better. It would create character development