Trapped in the facility that they once believed to hold the key to their cure, six people infected with the virus known as Medusa were left after a frenzy killed all the other former study patients. Now, the only ones left of the six are the medic Ron, the hacker Marco Owen (the only one not actually infected), a young boy named T, a woman named Katherine who is rapidly succumbing to the disease, and a young girl named Kasumi.
Chased by strange dinosaurs, Jefferson, the boy, Katherine and Kasumi are heading to Marco, who has gone ahead of them to drain the water from the complex so they can enter the dangerous secret level. He has just found out that a former fellow hacker and rival named Zeus is behind the whole thing. Patient Zero of the Medusa virus is still alive as well, a Russian herder girl who manifested her formerly imaginary friend and had to kill it to save her family- who coincidentally died in the fire she set when it burned down their home.
But the strain of Medusa that she caught was not very powerful, and Zeus seeks a new victim, one with enough imagination to remake the world and a strong enough strain of the virus to do so. The person he seeks is one of the survivors... but who? Only Zeus knows, but he laughs at the struggles of the survivors while they try to figure out his plan.
Katherine became very attached to the boy who was a survivor along with her. He reminded her of her son. But now that she dies while he is in peril, she sacrifices herself and her body cracks and falls away to reveal a strange bird-woman body underneath. One strong enough to protect the boy and keep him safe, along with the others. But in protecting them, she is injured, and when they find a locker room, they change their tattered clothes for new ones. Kasumi finds a party-type black dress to wear, and nothing else. Ron lends her a shirt to put on over the dress, and they leave Tim and the transformed Katherine in safety while they look for Marco.
Marco has been talking with Patient Zero, and now that she has the information she needs, she leaves. But Marco is okay with that. He has the information he needs, too. He drains the water and heads down into level 4, finding the Venus Gate. Getting it open, he is confronted face to face by Zeus, and while Marco threatens to kill his fellow hacker, the door clangs shut behind him, leaving the corridor empty and deserted again.
Kasumi and Ron enter level 4 to find it dark and deserted. They find a power box, and Kasumi turns it on, but she's still worried by what her sister, Satsuki, was doing in the complex on the day she entered. it was Kasumi who was chosen for the cold sleep, not Satsuki, so she wonders why her sister would even need to be here. But the light reawakens the thorn vines, and she is cut off from Ron by their growth. Attempting to make her way out of the thorns, she runs into Patient Zero, and follows her to Lab #2 on the fourth floor. The girl who is Patient Zero, named Alice, tells Kasumi more about Medusa, and then shows off her true body. The adultish girl who appears in the complex is not her true body, but a ghost composed of Medusa. Alice's real body is little more than a stump, and still the size she was when her family died.
All that is left of her is part of her upper body, her head, and her arms. She isn't sure how she is still alive, but is sure that Medusa is responsible. The people who built the complex wanted to use Medusa to change the world, and they built a dream machine that could force Alice to dream, and Medusa made the dreams come to life. But the machine was flawed. Dreamers have to wake up sometime, and when they do, the dreams crumbled, as did the constructions of Medusa. But Zeus changed that. He fixed the machine so that the dreamer would never stop dreaming. Even now, both of them are in a dream. The sleep capsules were actually machines to make the people within dream.
Marco, meanwhile, is found by Peter, the Scientist, who is dead but has come back to get revenge on the people who stole his original cold sleep capsule. He's constructed a new body out of Medusa and bugs. But the capsule is inside the monster who lays the eggs that hatch into more monsters. Zeus finds them and calls Marco out for being weak. Zeus has already slipped the bonds of his old body and made a new one from Medusa for himself. He has his new patient Zero inside the monster and plans to remake and rule the world with his powers of Medusa. And he's created monsters from the former medusa patients to help him do it...
Meanwhile, Alice asks Kasumi about her sister Shizuku, and Kasumi fills her in. The two were identical twins in body, but opposites in personality. When they caught Medusa together, they took an oath to die together if they had to. But when Kasumi despaired and tried to end her life because she couldn't live with the idea of her sister dying first without her, Shizuku became very angry and would no longer talk to her. Finally, on the day Kasumi was to go into her cold sleep capsule, they finally talked and made up, agreeing to look for each other after a cure was found.
Alice tells her that Medusa arises out of emotional hurt and pain, and that the thorns seem to grow to find Kasumi and stop growing when they finally find her. Kasumi thinks the thorns are the work of Shizuku and are looking for her, and Alice tells her to find the new Patient Zero and try to calm her down and find out why she is so emotionally damaged. Perhaps she can save them both if this occurs. But as Kasumi heads off to find patient Zero, Marco is fighting, and nearly dying at the hands of Zeus' Pantheon of monsters. Can Kasumi stop the madness in time and save her friends? And who is Patient Zero, anyhow? And what connection does she have to Kasumi and Shizuku?
I love this series. It's like a little ouroboros worm winding around and around and around. occasionally it leads to new information but it's dark and twisty and makes you think about uncomfortable things as it slowly winds around in time. We have gotten more information about Medusa, but now Medusa is a secondary thing. Now that we kind of know how it works, the story winds back around to the problem of what is going on and who is behind all of it.
First we thought it was Venus, and then we thought it was Zeus. But Zeus isn't really behind all of these weird manifestations- he's just using them to get power, and if Kasumi and the others can wake up Patient Zero from the dream that he or she is having, Zeus will lose power and no longer be able to twist the Medusa manifestations to his liking. Given that Zeus's body is now a Medusa manifestation, he could even die when whatever person is powering this whole thing finally wakes up.
This is an unusual manga. It comes closer to being Seinen than Shonen, because the story is almost uncomfortable to read. It's definitely rooted in a sci-fi or fantasy-ish version of the real world, but aside from Medusa and its powers, there aren't that many fantastical elements. And yet, it's that same uncomfortableness that makes it so awesome. It makes you think, and think deeply, when most Shonen manga are little more than puffs of fluff. Other series are meringue, this one is steak- you'll spend a lot more time chewing it over in your head because of all the weird and twisted stuff going on. Highly recommended.