As a Fridge subpage, all spoilers are unmarked as per policy. You Have Been Warned.
- Lucy frees Mayu's puppy because her puppy was beaten to death when she was younger.
- This is a more minor case, but Mariko's four viable clones are named Alicia, Barbara, Cynthia, and Diana.
- Lucy's real name is Kaede. It was right in front of us the whole time: The main characters live at the Maple Inn.
- Bando being told that in order to receive treatment and new limbs after his first encounter with Lucy, he'd have to literally give up his balls. He is understandably angry at why they would even say that especially without any explanation. But then in a Flash Back with Kurama, it's shown that men who've been touched by vectors from Diclonii and have children afterwards will birth more girls with that condition. Not that Bando was likely to want any, but they still didn't want to take any chances in case he did.
- Lucy's refusal to work with and later her decision to kill Professor Kakuzawa, in his plans against his father. At first it just seems Lucy being Lucy, but late in the series we learn that the Kakuzawas were never the Diclonius they thought they were. Since by that point it was established Diclonii could sense each other, a sharp reader would realize that Lucy never did, nor did she mention it with the Professor.
- Kouta learns Lucy's true name (Kaede) just before meeting the twins she reincarnated as. Kaede or Maple Trees have leaves with twin seeds.
- By the epilogue, humans have - through a combination of infanticide and genetic engineering - driven Diclonii to extinction. It is an irreparable part of recorded history. Thus, when another Human Subspecies arises, they will know that they will have to exterminate humans or be exterminated in turn. And when yet another subspecies rises from them, they'll likely declare genocidal war against humanity's heirs. And that's if humanity doesn't exterminate itself due to over-aggressive or stupid genetic policing to prevent themselves from mutating again. Holy Censored Angrish this universe's human race is screwed beyond all recognition.
- Tomoo is one of the most evil characters in the series, tormenting Kaede endlessly and killing her puppy just for fun, but how did he become that way at such a young age? It is possible that before he lived in the orphanage, he had Abusive Parents who were as bad as he was, or even worse.