Status in Japan: 5 volumes (ongoing)
Dae's Status: 2 volumes T___T (and I spied vol.3's RAWS!)
This series is still running in Japan, so consider this page still under construction :3 !

As a loyal fan of Yamaguchi's works, it's obvious that I instantly noticed the worth of this wonderful series.
Those of you may be familiar with two other works of Yamaguchi that sealed his popularity: Kakugo no Susume (released in the USA as Apocalypse Zero) and Shigurui. Well, Exoskull is pretty much a mix between the two: it has got the same backstory, setting and protagonist of Kakugo, but it fully embraces the cold, tragic and "serious" mood of Shigurui.
It was a true discovery and a confirmation at the same time: here Kakugo wakes up as a recurring hero, apparently to protect the humans, but he's thrown, with his fellow heroes, in a world were humans evolved the "wrong way", turning into bloodlusting monsters.
In such a situation, can a hero do his job and protect humanity? Can he protect something that he has no relations to and has no way to relate to..?
What does "justice" mean if it has no longer a practical need..? What is left to fight for in a world ruined by humanity itself..?

Before we find an answer to such questions, let's take a peek to the main characters:

Kakugo is the protagonist of this series; he used to be a hero of Justice, but as many before and after him, he was sent asleep the cryogenetic way in a peculiar structure during peaceful times, so to be re-awaken during a crisis.
So, at the beginning of the story, he finds himself awake in the dismissed facility after what looks like a good number of centuries.
As a fine warrior whose mission is to protect his safety and instinct is to answer vigorously to any kind of threat, he manages to get out of the facility, now turned into a harvest of sort-of-zombies and potential enemies only to realize that the world as he knew it is gone.
He's portrayed as a dutiful, yet cold and dull person, and it's impossible for him to relate to others if not under the options of enemy and foe: whoever attacks him is a foe, and it places him in an extremely solitary and desperate situation in this hostile world where nobody gives him proper orders.
The only thing that he can cling to are his ideals, but they have no longer any practical application. As Kakugo tries to find his mission in this desperate world, assuming that he was re-awakened for a reason, he's also destined to change and develop as he get to meet the other heroes and deal with their "arrangements" for existing.

TAKERU TSUKUMO (Exoskull Hyaku)
Takeru is the first hero that Kakugo meets after he gets out to the facility and he has no problems to detect him as a foe.
The boy followed our protagonist in his awakening and is quite pissed at how he just killed everything and everyone around him, without realizing that the "monsters" that he attacked and kept attacking are actually the "evolution" of the human race.
During the years, humankind and the planet were destroyed by the abuse of nuclear energy and weapons, turning the Earth in a barren land that can't bear any fruit and life anymore. Facing such a crisis, humankind reacted as it could: some used cyborg technology, other turned into vampiric creatures and the strongest ones evolved in a new form of life, monstrous and wild in its look and behaviour, but the rightful successor to the world in Takeru's opinion.
Takeru was born with a degenerative, genetic disease that make his body like that of a jellyfish: deprived of a solid skeletal structure, his skin transparent like jelly, he was destined to certain death-- But scientists developed his body artificially, updating it as Takeru grew up suffering unspeakable pain-- But it was through will and mental strenght that Takeru could finally be allowed to live, and even turn into a hero.
When he had to face the harsh reality of this new world after re-awakening, after the initial confusion, he immediately decided to protect the "monstrous" humanity, 'cause he can see and sympathize with the pain and suffering that it had to go through to finally "stand on its feet" instead of giving up to desperation.
Since Kakugo would rather fight for a more "conventional" kind of humanity, the two have to fight, and in the end Takeru is defeated.
As a parting gift to his favourite humanity, he allows his body to be eaten by the monsters as further nourishment, a vision that moves Kakugo, making him realize what a bright hero Takeru was, after all, and regretting his actions.
Later Takeru's rests will be collected by Mio and the boy will be brought back to life thanks to Ren's technologies.

RIKKA HATSUYA (Exoskull Yuki)
Rikka is the second hero that Kakugo meets after facing the desperation of Takeru's death and his inevitable, absolute loneliness.
The boy was still wandering the desolate lands when Rikka appeared like an angel, letting Kakugo come to his senses thanks to the touch of her hand on his cheek, the first human contact that Kakugo had in weeks.
Rikka is actually a hero on a run: she's the betrothed of Ren, unable to use her armoir and leave the castle, she decided to leave Ren's side, unable to accept his points of view, expecially concerning the mysterious "Medusa Project".
She's a cheerful, chubby and resourceful girl. Her optimism and hopeful views are healthy for Kakugo's mind, who easily gets used to the girl's company despite his cold personality.
It's also interesting that, despite Rikka's association to snow, she's always compared to warmth and light, in a positive contrast to Kakugo's experiences 'til then.
Rikka realizes that with the help of Kakugo she can wear her armor again, and together they managed to defeat Exoskull Hyou and Exoskull Tei, now wore by two "humanoids" created by Ren.
After Kakugo manages to defeat Mio, who was sent to fetch Rikka back, both are headed to the castle to meet Ren.

REN DOUCHI (Exoskull Shinden)
Ren is introduced as the "antagonist" of the series; he's a muscular, huge boy who's portrayed as the strongest "Exoskull" around.
He's perfectly aware of the situation the world and humankind are in, and for this reason he conceived the "Medusa Project", a mysterious plan involving cybernetic and the very use of Exoskull armors to prevent the extinction of mankind... What it involves and means, we don't know yet, but it's obvious to see that not everyone agrees with his plans: Rikka, Takeru and other heroes (defeated by Ren in the process) don't hesitate to show their discontent with it.
For now Ren keeps walking toward his "mission", though, organizing his forces in a military fashion: with a castle as headquarter, his personal guards as supports, he wanders the desolte lands looking for allies in other heroes-- or foes.

Mio is Ren's little sister, and the first of his personal guards.
She was afflicted by paraplegia since birth, but she still managed to support and cheer her big brother during his missions as a hero; the two are very close, and always relied on each other since they were kids.
In the current era, Mio was presented a full cyborg body and she can now serve Ren as a personal guard.
It's explained that her whole body is artificial, and her brain is the only human part left.
After she was defeated by Kakugo, in a quest to get the privilege to meet Ren, she's forced to allow the meeting but she's extremely disappointed by both Kakugo and Rikka's behaviour and plans revenge.

So, what can I say.
We're used to SciFi and sentai series by now, but I found this interpretation of the cliques quite intriguing and worth a few words.
The first point raised by this series is what justice is, and what it means once you have no way to pinpoint it to your scale of values. It goes deeper that that, it questions the dignity of being a "human", what it means besides the "naturalistic" concept of men as a mere "evolution" of other animals.
By placing a solitary hero in a contest where he can't get support from other people, encouragement from fans and allies or the words of gratitude from those they protect, Yamaguchi forces them to deal with their very essence of "humanity", and he forces them to impose their ideals to the harsh reality in a hopeless quest to Duty as "Identity".
Another extremely interesting idea is that of the "broken" group: the Exoskulls, this invincible squad of armored heroes, always acted singularly during the years they were "operative", but now they are awakened at the same time.
This would mean that they have to work together, and everyone of them, despite the "automatic" declaration of hostilities are aware of this fact: the unbearable solitude, the need of inspiration and support that every character feels and needs sure bring to this conclusion-- But none of them is still capable of this act of salvation, they are all alone in this desperate journey: the references to the Divine Comedy in the first chapters and manga's volumization sure are there to point to it.
Rikka is introduced as the "Beatrice" of Kakugo, the merciful soul that cleans away the poor boy's desperation thanks to hope.
Kakugo during his wandering thinks about the difference between desperation and hope, and he indentifies both as "diseases of the soul": but as Desperation is a disease that leads to death, hope is a disease that leads to life.
So, what started as a journey through desperation for all of our heroes, is slowly turning into a journey through hope-- Let's see where it'll lead them.

A few words are also due concerning Yamaguchi's artwork.
I was positively entertained by his almost "playful" art style in older works, that "rounded", satiric touch that turned everything into a groteque joke... By browsing through the pages of Exoskull you can tell that Yamaguchi really lerned a harsh lesson while working on Shigurui: his trait got more mature, "serious", but it still mantains that vivacity and freshness during the humoristic scenes and expressions... It's incredible how much this author improved during the years, and it's almost a crystal clear that he did that through sheer hard work...
Yamaguchi sure appears as a terrible rival for his colleagues.