In the year 2046 humans are moving away from using robots and begin to trust them less and less. In this time life becomes very perilous for the beings known as seconds. The seconds are the most recent line of robots, as far as the public knows. This is the world Detective Ross Sylibus lives in. Detective Sylibus is transferred to Mars by his request after his partner was killed by a robot. As he arrives he falls headfirst into a murder where a country singer on his flight was murdered. He steps off the plane and watches as a scene unfolds and he meets his partner, Armitage a female cop with a major attitude. A rash of murders begins when yet more women are killed. As the investigation is continued a secret is uncovered. There is another line of robots known as Thirds. More and more Thirds turn up missing, as a serial killer who is intent on wiping out all the Thirds runs rampant. Armitage in her quest to put the murderer to justice reveals a secret. She herself is a Third.

In the wake of a third world war which left Japan in ruins, an organization known as Vischio seized control of Tokyo and renamed it Toshima. Taking place in its back alleys are battle games known as Igura, overseen by the Vischio, in which contestants battle and bathe in each other's blood to earn the chance to go up against its tournament's king, Il-re. Igura is not the only fighting tournament around; Bl@ster is a similar yet vastly different game since it prohibits murder and the use of weapons. The only way to win is by knocking out the opponent. Akira, a young man isolated from his family, is known to be undefeatable at Bl@ster. However, his life on the top is shattered when he is accused of murder. Unable to prove his own innocence, all hope is seemingly lost... that is until a mysterious woman named Emma appears and offers him a chance. Now, to regain his freedom, Akira must participate in Igura and ultimately defeat Il-re.

Akari Mizunashi continues her training to become a Prima Undine (a professional tour guide gondolier) along with her friends Aika and Alice in the peaceful city of Neo Venezia. Despite the fact that these three girls are from competing companies, they are constantly together, learning more about how to become better tour guides and more about the mysteries of Neo Venezia. As the group continues to meet interesting and unforgettable people through their daily routines, they will also come closer to the secrets that make the enigmatic and ever beautiful city of Neo Venezia so warm and alive. Welcome back to Neo Venezia: the city where miracles can be created by hand.

In the 24th century on the planet Aqua, three girls—Akari Mizunashi, Alice Carroll, and Aika S. Granzchesta—continue to work hard toward achieving their goal of becoming Prima Undines: professional tour guide gondoliers. Luckily, the girls have the guidance of the three best Prima Undines in Neo-Venezia—Alicia Florence, Athena Glory, and Akira E. Ferrari—who are known as the "Water Fairies" in honor of their skill. With their help, the young apprentices train hard and work to overcome any situations that they find themselves in. Aria The Origination follows the hardships and daily lives of these three young girls, who are doing their best to improve as tour gondoliers in Neo-Venezia, a terraformed replica of Venice.