Shougo Mikadono's father has just passed away, and now he must become the head of Mikadono Group, his father's company. After completing the training to take over, there is just one other stipulation he must adhere to: he will need to find a girl he loves at his new school and marry her by the time he graduates high school. Shougo transfers to Miryuin Private Academy, and it seems like he has many girls to choose from, such as Konoe Suruma, the class representative as well as his first new friend; Miyabi Kannagi, a standoffish but kind girl; Rinka Kunitachi, the student council vice president; Mei Sagara, who runs a cafe and dresses like a witch; and Mana Tendou, the student council president. However, there is a complication: one of them is his long-lost half sister, and he has no idea which one, so how can he become romantically involved with any of them? [Written by MAL Rewrite]

Once a prize-winning violin prodigy, Hajime gave up on music after his father, professional violinist Ryuuji Aono, was involved in a scandal that led the media to harass his family. Now living alone with his mother and entering his final year of middle school, Hajime struggles to find a new career path. However, the sound of his classmate Ritsuko Akine playing the violin inspires Hajime to dream of a musical career once more. With the help of Ritsuko, Hajime prepares to take the entrance exam for the prestigious Umimaku High School. But if he wishes to join Umimaku's orchestra, Hajime must overcome his past trauma and open himself up to new musical horizons.

Hikaru Amatsuga's days of tranquility come to a sudden end when he rescues Alma, a mechanical arm crying for help. Alma fuses with his jacket, introducing Hikaru to the world of mechanical arms: mysterious, sentient weapons that normally become a part of their users' bodies. Forced to flee for his life, Hikaru is eventually captured by Aki Murasame, a twin mechanical arms user working for ARMS, an organization that protects the machines against unethical treatment. The Kagami Group, a nefarious organization that treats mechanical arms as mere tools, seeks to recover Alma. Hikaru is deemed a failure by ARMS for his lack of natural predisposition to be an mechanical arm wielder, so Aki is assigned to be his bodyguard. But Aki is defeated by Jun Kagami, who cruelly tears out her two mechanical limbs, condemning the girl to a slow death. Unwilling to abandon Aki to her grim fate, Hikaru miraculously awakens his power and neutralizes Kagami. Now a full member of ARMS, Hikaru is determined to unravel the truth about mechanical arms and protect his newfound friends and allies.

Second part of Gokushufudou.