Kouya’s life is full of misfortune. Every company he works for ends up going bankrupt and his apartment went up in flames. Now he’s a lecturer-in-training at Kaminekosaka Academy and also helps out at his grandfather’s neko cafe Nekotama-ya, which is staffed by three beautiful girls: the energetic Mike, the timid Ameri and the milady Persia. All three of them had feelings for him, and due to his misfortune, they all confessed to him at the same time. He didn’t want to lose this lucky chance and they all ended up spending the night together as a foursome. The next morning was the beginning of a new relationship between the four of the them, with all three girls being his lover at the same time! ...

March 1956.
Tokyo; a metropolis finally starting to recover ten long years after Japan's defeat in the War. Private eye Tokisaka Reiji accepts a strange request from a girl in Inokashira Park.

"I want you to look for something. Me. My true self."

Meanwhile, a series of bizarre murders is plaguing the area, one where young women are disappearing, only to turn up dead and maimed with their wombs torn out. Seeking assistance on the case, Detective Uozumi Kyozo called up his old friend and former coworker, Reiji.

Ouba Girls Academy, a school on the outskirts of Hoya City. Reiji's little sister attends this school, where two young women have mysteriously vanished. Saeki Tokio, the vice-principal, calls in Reiji to investigate their disappearance, giving him his third case.

Reiji infiltrates the academy as a substitute teacher to glean information from the students - but that's when he meets her once again.

Kuchiki Toko - his first client, the girl who asked him to search for her true self. Her manner is distinctly boyish as she remarks:

"Heya - so we meet again, Mr. Detective."

The body count continues to rise. What should be a simple search for some students is starting to grow out of control. For some reason, the number of missing people and unidentified bodies don't match up.

Who will be chosen as the next victim?

As the endless cycle of tragedy continues, what mysteries lie behind these new cases? Behind a similar series of murders from six years ago?

Perhaps one girl's smile might await beneath the shell of tragedy... ...

The protagonist, Naohiro, and his wife Risa have been married for 4 years. Their married life is smooth sailing, and the good relationship between them is enough to be envied.

Except for one feeling born from Naohiro's heart...

It all started with a small incident. One night, when the couple was happily drinking together, Risa talked about her ex-boyfriend, and after the conversation, Naohiro felt a strange excitement.

Feeling weird, he searched the internet about it, and while doing so, realized that he does indeed have "that" fetish.

However, he can't possibly tell that to his beloved wife, but the more they find happiness with each other, the more stinging sensation torments him from within.

Then one day, one of his juniors back in school, Tsukasa, consulted him about something...
...

"The creatures of the demon world known as "succubus" use a male's sexual energy, his "technoforce" as their nourishment.
One day, one such succubus known as "Lovelia" appears suddenly before the main character to steal the power of his lust, known as his "technoforce".
Considered to be one of the greatest beauties in 1000 years, Lovelia may look bewitching, but the truth is that this is her first ever work assignment and she is very naive when it comes to men.
Lovelia tries again and again to steal away his technoforce, but her innocence gets in the way of any real progress.

Unless Lovelia succeeds in harvesting the technoforce of the one she has chosen to possess, she can't return home to the demon world, nor can she possess another man. ...Lovelia finds herself stuck living together with the main character."

"Can Lovelia successfully harvest technoforce?!
Set in Akihabara, the awkwardly funny and slightly naughty new life of one naive succubus begins!" ...

"You're the idol you used to sing to on stage?"
After their first live performance, Nobuyuki and Ai have a fateful encounter with the top idol, Nagisa Yukihiro.
Six months later.
With Miwako's kindness, Nobuyuki and his friends attend a joint lesson with Uesugi Productions, a long-established entertainment production company.
While getting involved with Nagisa through joint lessons, it is decided that an idol festival - DivaFes - will be held, but...

"What are you going to do?　What do you want to do as an idol?"
"I want to join in--no, I want to try!"

DivaFes in a joint lesson, and Ai takes on the trial to take the next step as an idol.
...

In the near future, a sudden and unexplained sea rise has left much of human civilization underwater.

Ikaruga Natsuki, a boy who lost his mother and his leg in an accident some years earlier, returns disillusioned from a harsh life in the big city to find his old countryside home half-swallowed by the sea.

Left without a family, all he has to his name is the ship and submarine left to him by his oceanologist grandmother, and her debts.

His only hope to restore the dreams for the future that he has lost is to take up an opportunity presented to him by the suspicious debt collector Catherine. They set sail to search the sunken ruins of his grandmother's laboratory in order to find a treasure rumor says she left there.

But what they find is not riches or jewels; it is a strange girl lying asleep in a coffin at the bottom of the sea.
Atri.

Atri is a robot, but her appearance and her wealth of emotions would fool anyone into think she's a living, breathing human being. In gratitude for being salvaged, she makes a declaration to Natsuki.

"I want to fulfill my master's final order. Until I do, I'll be your leg!"

In a little town slowly being enveloped by the ocean, an unforgettable summer is about to begin for this boy and this mysterious robot girl... ...