Twenty-six-year-old Hiroto Suwa; his wife, Naho; and their old high school classmates—Takako Chino, Azusa Murasaka, and Saku Hagita—visit Mt. Koubou to view the cherry blossoms together. While watching the setting sun, they reminisce about Kakeru Naruse, their friend who died 10 years ago. Mourning for him, they decide to visit Kakeru's old home, where they learn the secret of his death from his grandmother. Filled with regret, Suwa and his friends decide to write letters to their 16-year-old past selves to set their hearts at rest. With the knowledge contained in the letter from his future self, 16-year-old Suwa has the chance to rewrite the future. What choices will he make? What will happen in this new future? [Written by MAL Rewrite]

Shintarou Kisaragi—a NEET who shut himself inside his room for 2 years—has been living his life normally until he met a cyber girl named Ene, who appeared in his computer screen when someone anonymously sent him a mysterious e-mail one year ago. One day, Ene had been messing with Shintaro's PC, which causes him have to go to the outside world for first time in two years. (Source: Official site)

The group of privateers known as the Blue Steel continues their mission to deliver blueprints of the Vibration Warhead Torpedo—a weapon that may turn the tides of war in their favor—to the United States. However, a new threat arises from their enemy, the overwhelming Fleet of Fog in the form of "The Student Council.," This is a group of warships composed of the remaining Mental Models—the ships' humanoid avatars—who have yet to face the unpredictable captain of the Blue Steel, Gunzou Chihaya. As the Blue Steel gets closer to understanding the origins of the authority controlling the enemy, Iona's past starts to reveal why the war began and her reason for siding with humanity. [Written by MAL Rewrite]

Recap of the first 9 episodes.