Near the beginning of the visual, the protagonist, Shouta Tanaka, and his class take a trip on a cruise ship when a disaster happens. The ship sinks, and Shouta is carried out to sea; later waking up on a nearby island. Shortly after, he meets up with some of the survivors, consisting of five of his female classmates (Kisaragi Rei, Yumi Nagoshi, Shiho Ouma, Akira Toume, and Ai Himura), his teacher, Aoi Inoue, and an unfamiliar face: Ichijou, who introduces herself as a University doctor and explains that she was on the lifeboat which carried his fellow students to the island.The group finds an abandoned building which happens to contain enough food to sustain them. They sleep there for the night, but the next morning, several of the students are horrified to discover a female corpse clutching a briefcase. Ichijou reads the documents found within. She says that the island was some kind of research facility, and that the staff there were testing out a new virus, as well as a vaccine. What's worse, the virus leaked and has since become isolated to the island. The doctor tells everyone to remain calm, but also states that the chances that one or more of them have come in contact with the virus is likely. She promises to investigate the matter further.
When everyone else leaves the room, Ichijou thanks Shouta for being brave enough to pry the suitcase from the corpse. She asks if she can draw some blood from his fingertip for a blood test and then sends him on an errand to get blood samples from all the other females. Shiho is a little suspicious; claiming that Shouta was too quick to trust a complete stranger and that only the doctor had been permitted to lay eyes on what was really in the "virus" report. Their teacher, however, squashes these claims, saying that they should be thankful to have a doctor by their side during this time.
Shouta is successful in getting everyone to cooperate. He returns to Ichijou with the petri dishes, and then has his own blood taken by the doctor, as he had agreed. Without warning, Ichijou then begins sucking on the finger that she just pricked and from here, continues to gradually advance on him sexually. After his climax, Ichijou quickly apologizes for her lack of restraint. Shouta bears no ill-will at all, however, and the two agree that the incident will just be their little secret.One week passes, and Ai suffers a serious and acute illness. The doctor is quickly called in to help. She asks Ai if she has had any strong sexual desires recently, and to please answer honestly, stating that her symptoms are resembling that of what she translated from the report. Ichijou further clarifies that the virus only affects women, and as ovulation nears, if left untreated, the it causes respiratory seizures which eventually result in death. The students plead for her to help, but Ichijou states that no cure was mentioned in the report, and that there is only one given way to slow, suppress and control the seizures.
The afflicted must take fresh human semen into he womb.
Ichijou adds that the results of the blood test were produced, and that every one of the females, herself included, has been confirmed to have shown a positive reaction with the virus. Urgently, the doctor encourages Shouta to give Ai his seed as quickly as possible. However, Ai has a great repulsion for him; having even cruelly bullied him in school back in Japan, and upon hearing this request, she goes into a violent seizure which ends up killing her.
Everyone begins to panic, but Ichijou states that Ai's death was not in vain, for that it may lead them to discover a solution. That night, Shouta goes to visit the doctor, who tells him that his timing is perfect. She begins to undress, stating that she is thankful that he came by to "help suppress" her viral symptoms. Wanting to do all he can to help in this unexpected crisis, Shouta agrees to have intercourse with her. Afterwards, she attempts to motivate him by building up his confidence; stating that he has the ability to be "the savior of everyone".
Shouta receives oral intercourse from the five other island inhabitants, but gets harsh words and a hard slap the next day from Kisaragi, who is not at all pleased at the way he selfishly handled his private time with Yumi, her close friend. Feeling terrible, Shouta rushes to a outside cliff with intentions of committing suicide, but stops when he spots a cave down by the shore. He decides to check it out, and finds Ichijou there. She tries to ease his distress, saying that her intended solution may have backfired. He tells her that it was by no means her fault, being grateful to have forged a friendship with at least one person on this island.
Ichijou informs everyone that may have found a way to kill the virus: Pregnancy. Kisaragi is outraged to hear such a thing and says that it is just an excuse to enable Shouta's "perverted desires", but Ichijou is quick to accuse her of being selfish; stating that if she chooses to die foolishly, that's one thing, but she is also threatening the lives of the others, like Yumi. She also reminds them that each day that they receive his seed is another day that they get to live for when help finally arrives.
Shouta continues to have intercourse with the teacher and the four students numerous times as the weeks goes by, and before long, the aversion that each of them had towards him quickly transforms into acceptance, obsession, and lastly to the point that they become enslaved to his sexual prowess.
A new day comes, and Shouta decides to take a break and explore the island some more. He sees the watery cave from before, which he had nearly forgotten about until now, and decides to venture in once more. He is shocked to see a handrail, a ladder, and then even a functioning motorboat inside of it. He contemplates whether he should use it to escape or alert the others, when a strange light coming from a downward staircase catches his eye. He discovers a sterilized room with shelves filled with countless chemicals, as well as a laptop computer.
Succeeding in cracking the password with little difficulty, he discovers a file named "Jinguji", which just happens to be the name of the academy that he and his classmates attended. It contains a roster of his entire school, with names, birthdates, classes, addresses, emergency contacts and photographs. He is then shocked to see checkmarks next to each of the six women who drifted to the island with him. He recalls Ichijou's claim that she had been on board by "accident" and that she never presented anything to prove her identity. He then remembers how hastily she lured him away from the cave the first time. He comes to the conclusion that this is, in fact, the doctor's private room, and that her biggest goal may not be to escape the island after all.
It is here where the story branches towards different endings.
Shouta believes Ichijou's claimsEdit
The motorboat only holds two seats, meaning that Shota can only escape with one person. If he chooses his teacher or one of the four classmates, they leave the island in secret, and Ichijou is not mentioned again. It is quite possible that from here, she packs up and leaves to become Mistress in "Revenge Room".
If he chooses Ichijou herself, however, Shota stays on the island and creates a harem of sex slaves out of the teacher and classmates, while also continuing to engage in consensual intercourse with the doctor, resulting in a happy ending for her.
Shouta is suspicious of Ichijou's claimsEditThe protagonist goes back to the chemical room the next day, but this time, is discovered by Ichijou. Shouta demands the truth from her, which - with a wide grin - she gladly tells him: She is the one who created the deadly virus. When asked why, she replies that it was a microcosm experiment; to witness what the impact would be like if it was released out into the world. When prodded again as to why, she replies simply that she felt like doing so, though also adding that the virus was created initially as a way for her to murder her rival - the female researcher who the aforementioned corpse belonged to. As for why she chose his school, it was simply the luck of the draw. The timing and location of their extracurricular cruise couldn't have been more impeccable in fitting into her schedule.
Finished with her explanations, she then reaches out her hand, saying that she wants Shouta to be her partner from now on. It is at this point that two more ending paths are offered.If he accepts, he continues on as her research assistant and sexual partner. If he declines, Ichijou expresses her disappointment in how blinded he is by his morals. He then corrects her, stating that he thinks her experiment is excellent; that without it, he would have continued to have been ignored and/or bullied by the rest of the women on the island. It worked so well, in fact, he adds, that he now wants the doctor herself in the same manner.
"What if you were to become infected with the virus, too?" he asks.
His question is met with laughter from Ichijou, who states that she's not stupid enough to have not taken precautions to protect herself from such an event. She then claims that if he wants her, he is certainly welcome to continue the relationship they've been having. However, as she approaches, Shota notices a sharp object in her hand. Thinking fast, he blurts out:
"You're a brilliant researcher, but perhaps you should have taken a moment to think about better security measures. Such as not using your first name as your password."
Taking advantage of the doctor's surprise, Shouta grabs her wrist, causing her to drop the shard of glass that she had intended to kill him with. He goes on to say that thanks to the information that he found on her laptop, he was able to create a concentrated sample of the virus, which he had kept hidden in his breast pocket this entire time. Shouta tackles the now-terrified doctor, binds her wrists with rope and forces the sample into her. In this ending, he again decides to stay on the island and form a harem, only this time he adds Ichijo to it as well. It is the only outcome in the game that involves some sort of punishment for her.
In the Anime VersionEditThe original video animation, with it's combined runtime of thirty minutes, condenses plot of the original game immensely. In this version, three students, Ai, Yumi, and Akira, have already suffered fatal heart attacks from the virus, leaving only Shouta, Kisaragi, Shiho, Aoi, and the doctor.
Ichijou has Shouta tell her details about his encounters with the other three as they make love, and even watch the ones that he video taped. Eventually, Shouta finds the doctor's cave, and confronts her, along with the other three females. Again, Ichijou confesses to have created the virus, and does not at all seem remorseful about it. From here, the animation goes the path of the "Harem + Ichijou" ending from the game, with all four women insatiably beholden to him.