200 day summer prolly would be ideal for someone not experiencing a timeloop, heat aside
if it's her cousin it's prolly pretty malicious/yandere of her, tho i wouldn't be surprised if some other forces got involved depending on how big this story got (if this wasn't an interpersonal based story i wouldn't be surprised if there would be some ppl out there trying to use her power or so)
she's so convinced she isn't in love with michiru and this isn't her being jealous.
I imagine her childhood was prolly quite busy/emotionally stressful dealing with her parents to ever have had a crush before, tho i wonder, maybe there's some lighthearted rom com version of some wise old lady who enjoyed long lasting marriage b/c she got to experience it twice as much (but i imagine it would make a lot of ppl unhinged unless they had a blessfully happy luxurious life lol)