A year has passed since the events of SSSS.Gridman. The world is at peace and no one except for Rikka and Utsumi remembers the kaiju, Gridman, or Akane Shinjou. This includes Yuuta, who despite serving as Gridman's host, has no memory of the most important moments of his life. So when a new Kaiju appears, he leaps at the chance to prove to himself that he too can be the hero by merging with Gridman once more. (Source: ANN)

Grisaia no Rakuen begins right at the end of the previous installment, Grisaia no Meikyuu. Kazami Yuuji is arrested under suspicion for terrorism. A video showing apparently concrete proof that Yuuji committed these acts, and he is held in custody by Ichigaya. Ichigaya knows full well that Yuuji didn't commit the crimes he has been accused of. But he did fail to assassinate Heath Oslo, who is the leader of the terrorist organization with an extremely devastating weapon in their possession. In fact, Ichigaya have their own plans for Yuuji... But all may not be lost for Yuuji. The girls of the Mihama Academy are not about to let Yuuji be used for political gain, and neither may the mysterious new figure which appears before them.

Having attended Mihama Academy for about a year, Yuuji Kazami has seemingly found his place within the school, but he suddenly decides to pursue a promotion in CIRS. After consulting JB about his intentions, they both thoroughly examine Yuuji's documents and dissect the events of his upbringing to determine if the job is fit for him. Meanwhile, unbeknownst to the two, the girls of Mihama uncover some torn documents in Yuuji's room. After restoring the papers, they discover the story that has formed—or perhaps broken—Yuuji into the man he is today. However, what was thought to be history has haunted him to the present, and the chains of the past begin to drag him back into the darkness...

A giant sea monster known as Dragonsaurus has emerged from out of nowhere, terrorizing the depths of the oceans. Great Mazinger, Grendizer and the Getter Robo G team join forces to combat the new threat. But their task becomes more complicated when Dragonsaurus swallows up Boss Borot and makes its way toward Tokyo. (Source: ANN)