Unbreakable Machine-Doll

Toujou Basara is a high school student whose father has suddenly just remarried. His father then departs overseas leaving Basara with two new beautiful step-sisters. Little does he know, his new sisters, Mio and Maria are actually the new Demon Lord and a succubus!? Almost trapped into a life of servitude, Basara forms a reverse contract by accident and ends up becoming Mio's master! Hijinks ensue as Basara finds himself in one ecchi situation after another. However, Mio's life is in danger as she is pursued by demons and heroes!

One day, humanity was invaded by another world. Having experienced that battle, known as Other World War I, humanity moved to marine floats, built for emergency evacuation purposes, as soon as Other World War II began. It's around that time that Kizuna Hida is summoned by his elder sister and visits the Strategic Defense Academy Ataraxia where he meets Aine Chidorigafuchi, a girl who uses Heart Hybrid Gear Zeros to fight the otherworldly enemies. He has a tough time dealing with her, but when her Gear runs out of energy, the only way to get it back in action is to do something lewd to her!

Illyasviel von Einzbern is an ordinary elementary school student who becomes a magical girl when the magical Kaleidostick Ruby deems her a more suitable master than the sorceress, Rin Tohsaka. Rin, who had been tasked by the wizard Zelretch to collect the seven Class Cards containing the spirits of Heroic Spirits from legend, finds that she is unable to change Ruby's mind and must supervise Illya in completing the task of collecting the Class Cards. During Illya's adventures, she receives a friend and rival in a girl named Miyu, the contracted master of the Kaleidostick Sapphire, which similarly abandoned its original master and Rin's rival, Luvia Edelfelt.

Invertia was a meteor storm that caused an unprecedented disaster during the 20th century. Because of this disaster, numerous cities around the world were destroyed. However, within the meteor, an unknown element called mana was discovered. It allowed human technology to make rapid strides giving rise to a new species of super-powered humans, the Star Pulse Generation (Genestella). The Festas (Star Warrior Festivals) host battles between Genestella at a city of six academies called “Rikka,” also commonly known as “Asterisk.” Scholarship student Ayato Amagiri transferred into Seidoukan Academy in order to fulfill his own wish, swearing he too will fight in this city.