if she's from Japan she should know well the concept of reincarnation.
each souls is thousands if not millions years old. but the person they are Live currently is a new. so even if she has memories from previous life she still a toddler to the core. she's a kid, just with extra memories. that all
so even he regrets the execution in the end, huh?
also didn't expect that girl to ended up dead as well in main timeline. the original plot is sure fucced up beyond dark