Cage of Eden/YMMV

Complete Monster: Hades and Nishikiori.
Epileptic Trees: Just about everything in the series.
Fan-Preferred Couple: If the forums of various sites are to be believed, then Akira/Rion is by far the most popular pairing, and for good reason, due to their willingness to protect and take care of each other, no matter what happens.
- Akira/Mami seems to be gaining popularity quickly, though.
Ho Yay: Kouhei really wants to find Akira. He also states that while he can't bear to show himself in front of Akira anymore, he will protect him from the shadows.
- Yarai and Akira have a bit of this, too. In Chapter 141, Yarai actually cries because he doesn't want to kill Akira, but Nishikiori won't save Kurusu-sensei if he doesn't.
Moral Event Horizon: Kouhei, up to then one of the nicer characters, kills a girl on the mere suspicion that she saw him stab the pilot.
- Nishikiori jumps over the line with every appearance. It really says something when the nicest thing he's done is send a bunch of kids on a suicide mission.
Nightmare Fuel: Being stuck on an uninhabited island with pretty much every large and dangerous species that existed between the extinction of dinosaurs and the end of the last Ice Age out to eat or maim you is not a Happy Fun Time.
- Well Meganeura extinct like 50 millions of years before dinosaurs appeared - and I mean first dinosaurs like human-sized at best (at least 150 million years before most famed dinosaurs out there). This troper still hopes for wandering T-Rex as... do we have a trope for Crowning Moment of Awesome and Nightmare Fuel in one?
- This hellish creature qualifies.
- Nishikiori's brainwashed slaves, who will continue serving him despite all logic and reason.
Squick: My eyes...
- In general, the manga doesn't pull any punches in showing exactly what teeth^[1] bigger than your head can do to you...
  - Or big falls.
Too Cool to Live: Zaji

↑ or beaks, or claws, or pretty much everything else

[1] r beaks, or claws, or pretty much everything else

[1]