The survival subgenre of adventure fiction is one that lives and dies on the number of deadly situations that the characters can believably (for a given value of the word) be put through. Yoshinobu Yamada's choice of an apparently prehistoric island is a good one in this sense, as it provides ample natural difficulties along with the more human ones, and within these two volumes we encounter poisons, diseases, rampaging beasts, and even the well-known danger of meddling with a wild animal's offspring. While it can at times feel too action-packed, Cage of Eden consistently delivers thrills and perils to its readers, and it is all too easy to sit down and read both of these books in one sitting.

Despite the addition of several new characters, or at least previously undeveloped ones, the main focus remains on the core trio of Akira, Rion, and Ohmori. Ohmori is the least believable of the three, standing back most of the time and letting the children make the decisions for the group. Granted, she is the “klutzy busty female” type, but she is also nine years older than the other protagonists, which really ought to count for something. That said, there are a couple of instances where she does prove both useful and instrumental, primarily for her medical and rescue know-how. For the most part, however, she and new adult Kurusu-sensei function as the mature eye-candy for readers, which is a bit frustrating. However the end of volume three may reveal that Yamada is doing this on purpose – when another group of non-student survivors is discovered, Akira finds something lacking in their attitudes; possibly this is in direct relation to Ohmori's passive behavior.

Fortunately Akira and Rion are characters whose survival is worth cheering for. Akira, categorized by his teachers and classmates as the class clown, is actually a natural leader. He is able to assemble a group, convince them to follow him, and even add to their number with his reasoned logic and willingness to look out for the others. It is worth mentioning that Rion, who has known him since early childhood, is unsurprised by this. One of the central themes of Cage of Eden is that people are not always who they seem to be. That Rion has always seen the strong person underneath Akira's clownish antics indicates that at least one person may be more astute than we've been assuming. Meanwhile, in a direct foil to Akira's competency, Kohei, the school “cool guy,” is struggling to maintain his mask. The contrast between his actions, inner monologue, and vocalizations are fascinating and draw a clear parallel between he and his best friend. Likewise the stoic and seemingly vicious Yarai clearly has something else going on, as does the apparently smart Yoshimoto. These character moments are just as compelling as the action plot and make it easy to draw comparisons between Yamada's work and other well-known survival stories.

One thing you will definitely find here that was lacking in, say, Lord of the Flies, is plentiful fanservice. Yamada enjoys drawing the female form in all its curvacious glory and he is not shy about flipping up skirts or low camera angles. In two scenes in these volumes, he also takes care to show two women smushing their breasts together as they cling to each other. More interestingly from an academic standpoint (if such a term can be applied to the subject) is the fact that Yamada seems to go out of his way to avoid drawing nipples while consistently outlining the labia of the female characters' vulvas. This seems considerably more risque than the gender-neutral nipple, but on the bright side it does show that he at least has a grasp of female anatomy. Presumably it is this tendency, plus the one shot of prehistoric rhino sex in volume three, that has earned these volumes their older teen rating, as the violence, while present, is well below the level of something like Higurashi: When They Cry.

Backgrounds and animals remain a highlight of these volumes, as Yamada's research shines through the fairly unremarkable character designs. Most animals have a familiarity to those of us who grew up with dinosaur books or took a paleontology class, and Mariya's explanations feel fairly well integrated into the text. One case, where the animal behaves differently than science always contended it did, proves especially interesting from both a story and a scientific point of view. It is also interesting to note that Yamada's animals operate according to Darwin's theories.

Cage of Eden has all of the elements of a classic survival epic – monsters, diseases, an unfriendly wilderness with no perceived escape, and our own ability as humans to lie. While it can be laid on a bit thick at times, and the fanservice or treatment of the adult female characters may be objectionable to some, Yamada's story is an engrossing one. If it drags on too long, it may be in trouble, but at this point, this series is not only a compulsive read, but an enjoyable one.