It’s My First Time Being Loved

As the only hope to stop the destruction of the world, she was forced to sacrifice herself for everyone in 99 lives. She just hoped this would be the last… She ended up starting her 100th life. They should treat her like a hero and sacrifice her again. That's what she thought, but:

“Thank you for being born safely”
“I’ll save you, little sister!”
“Why doesn’t our youngest show me her smile too?”
“My love, I missed you”

Is this life a little… strange?