The Makochan Kaihatsu Nikki subreddit (r/MakoChanNikki) has only 3,000 members, but it is fiercely active. Popular fan theories include:
Regardless of which side of the fence you land on, the series succeeds in eliciting a strong emotional reaction. It isn't a "safe" story; it is one designed to provoke thought (and other feelings) about the loss of innocence. makochan kaihatsu nikki