As a wild youth, elementary school student Shouya Ishida sought to beat boredom in the cruelest ways. When the deaf Shouko Nishimiya transfers into his class, Shouya and the rest of his class thoughtlessly bully her for fun. However, when her mother notifies the school, he is singled out and blamed for everything done to her. With Shouko transferring out of the school, Shouya is left at the mercy of his classmates. He is heartlessly ostracized all throughout elementary and middle school, while teachers turn a blind eye. Now in his third year of high school, Shouya is still plagued by his wrongdoings as a young boy. Sincerely regretting his past actions, he sets out on a journey of redemption: to meet Shouko once more and make amends. Koe no Katachi tells the heartwarming tale of Shouya's reunion with Shouko and his honest attempts to redeem himself, all while being continually haunted by the shadows of his past.

Denji is robbed of a normal teenage life, left with nothing but his deadbeat father's overwhelming debt. His only companion is his pet, the chainsaw devil Pochita, with whom he slays devils for money that inevitably ends up in the yakuza's pockets. All Denji can do is dream of a good, simple life: one with delicious food and a beautiful girlfriend by his side. But an act of greedy betrayal by the yakuza leads to Denji's brutal, untimely death, crushing all hope of him ever achieving happiness. Remarkably, an old contract allows Pochita to merge with the deceased Denji and bestow devil powers on him, changing him into a hybrid able to transform his body parts into chainsaws. Because Denji's new abilities pose a significant risk to society, the Public Safety Bureau's elite devil hunter Makima takes him in, letting him live as long as he obeys her command. Guided by the promise of a content life alongside an attractive woman, Denji devotes everything and fights with all his might to make his naive dreams a reality.

Takemichi Hanagaki's second year of middle school was the highest point in his life. He had respect, a gang of friends he could count on, and even a girlfriend. But that was twelve years ago. Today, he's a nobody: a washed-up nonentity made fun of by children and always forced to apologize to his younger boss. A sudden news report on the Tokyo Manji Gang's cruel murder of the only girlfriend he ever had alongside her brother only adds insult to injury. Half a second before a train ends his pitiful life for good, Takemichi flashes back to that same day 12 years ago, when he was still dating Hinata Tachibana. After being forced to relive the very same day that began his downward spiral, Takemichi meets Hinata's younger brother. Without thinking, he admits to his seeming death before flashing back to the past. Takemichi urges him to protect his sister before inexplicably returning to the future. Miraculously, he is not dead. Stranger still, the future has changed. It seems as though Takemichi can alter the flow of time. Given the chance to prevent his ex-girlfriend's tragic death at the hands of the Tokyo Manji Gang, Takemichi decides to fly through time to change the course of the future.

According to the Republic of San Magnolia, their ongoing war against the Giadian Empire has no casualties—however, that is mere propaganda. While the silver-haired Alba of the Republic's eighty-five sectors live safely behind protective walls, those of different appearances are interned in a secret eighty-sixth faction. Known within the military as the Eighty-Six, they are forced to fight against the Empire's autonomous Legion under the command of the Republican Handlers. Vladilena Milizé is assigned to the Spearhead squadron to replace their previous Handler. Shunned by her peers for being a fellow Eighty-Six supporter, she continues to fight against their inhumane discrimination. Shinei Nouzen is the captain of the Spearhead squadron. Infamous for being the sole survivor of every squadron he's been in, he insists on shouldering the names and wishes of his fallen comrades. When the fates of these young souls from two different worlds collide, will it ignite the spark that lights their path to salvation, or will they burn themselves in the flames of despair?