In the near-future Japan, global warming has brought the large city Yokohama underwater, and only the hills remain above the ocean surface. What used to be one of the largest cities in Japan now feels like a small town. Basically, the existence of the island country itself has been threatened. However, there is no feeling of desperation, devastation, nor hopelessness. People are enjoying laid-back lives, and they seem to appreciate each other's company, enjoying the quiet and peaceful time together. This is especially so with Alpha, a carefree young woman who runs a cafe, named Cafe Alpha. She enjoys her life immersing herself in the beautiful nature all around her. There is nothing more precious to her than spending quality time with her kind friends. Oh, the fulfillment and the joy she finds in life... it all indicates her to be a compassionate human being, but she is not quite a human. She is actually a type A7M2 robot. One day, upon hearing a radio forecast warning an approaching typhoon, her old friend who lives close by invites her to the gas station he runs, worried that her old cafe may not withstand the typhoon. Indeed, the passing of typhoon leaves Alpha with her cafe severely damaged. That's when she decides to go on a journey to raise money to rebuild her cafe, and also to see the outside world away from her friends and the comfort of a peaceful life.

Iroe Genma is a third-year high school student often referred to as "Elder Sister" despite her short height. This troublemaking teenager is the president of her school's Model Club, which is dedicated to building plastic models of various objects and structures, such as cars, boats, and even robots. Joined by her two underclassmen, the violent Hazuki "Okappa" Okamoto and the rational Makina "Makimaki" Sakamaki, the small group aims to carry out their club duties but are often sidetracked by a myriad of distractions. From battles between club members to lessons on how to confess to your crush, these three schoolgirls get caught up in all sorts of wacky, and downright outrageous situations!

These events occur in Westland, New York, during the 21st century. With a sharp knife, a murderer is indiscriminately killing people… A girl witnesses one of these murders, and the knife is turned on the helpless girl shaking with fear. Meg returns to this town with Joe to celebrate the “birthday” of Shirley, who used to live with Meg. Orphans, they had decided that the day they first met would be her birthday. In the past, Meg had taken care of three little children, including Shirley, just before meeting Joe. The children were then adopted by a police officer, Sam. He possessed a strong sense of justice and they are supposedly living happily together now. Meg and Joe happen to help a person and receive a reward. They buy a present for Shirley with the reward money and go to meet Sam. However, they notice him acting strangely. Upon questioning him, he explains that Shirley was assaulted by a murderer and seriously injured. Joe says to the grieving and angry Meg, “Let's exact revenge on the murderer for Shirley.” However, the murderer gradually approaches them from behind. The cruel black eyes fall on Meg and Joe… To make matters worse, a dark plot casts its shadow over Meg, Joe, Sam, and the whole town.

In the near future, there are people with special power called Sevens. It seems like the country has maintained peace by a company called Sumeragi Group, but they are the one who captured the people with the special power by force and did inhumane experiments. Gunvolt, the main character who has the power of Sevens, used to be in Feather, a resistant group who fought against the Sumeragi Group. The story begins with meeting the heroine, Sian.