Since he was a child, Ryuuichi Naruhodou's dream was to become a defense attorney, protecting the innocent when no one else would. However, when the rookie lawyer finally takes on his first case under the guidance of his mentor Chihiro Ayasato, he realizes that the courtroom is a battlefield. In these fast paced trials, Ryuuichi is forced to think outside the box to uncover the truth of the crimes that have taken place in order to prove the innocence of his clients. Gyakuten Saiban: Sono "Shinjitsu", Igi Ari! follows Ryuuichi as he tackles cases to absolve the falsely accused of the charges they face. It will not be easy—standing in his path is the ruthless Reiji Mitsurugi, a prosecutor who will stop at nothing to hand out guilty verdicts. With his back against the wall, the defense attorney must carefully examine both evidence and witness testimony, sifting through lies to solve the mystery behind each case. With a shout of "objection!," the battle in the courtroom begins!

Japan, 2019, just before the dawn of a new era. Suddenly, a rift to another dimension appears in the sky, revealing an alternative world "Shinkoku Nippon," with the sky and the earth upside down. This parallel world keeps their former militarism, with its era being Eternal Showa. The military invades the real Japan with giant humanoid robots called "Garann" and their gas weapons "Genmu", rendering our modern weapons ineffective. "Shinkoku Nippon" instantly seizes the government and achieves de facto conquest of Japan. The new era, "Reiwa," has not arrived for Japan.

Japan, 2019, just before the dawn of a new era. Suddenly, a rift to another dimension appears in the sky, revealing an alternative world "Shinkoku Nippon," with the sky and the earth upside down. This parallel world keeps their former militarism, with its era being Eternal Showa. The military invades the real Japan with giant humanoid robots called "Garann" and their gas weapons "Genmu", rendering our modern weapons ineffective. "Shinkoku Nippon" instantly seizes the government and achieves de facto conquest of Japan. The new era, "Reiwa," has not arrived for Japan.

To celebrate their graduation from university Kaori and her two friends visit Okinawa in southern Japan for a short vacation. At the vacation house, provided by Tadashi's uncle, a numbing stench awaits the girls, and can be traced to a horrendously deformed, legged fish that Kaori kills. More and more of these creatures appear and portend a horrific change for the animal life in the area. A phone call from Kaori's fiancé Tadashi in Tokyo quickly shows the scope of this epidemic, when he is also attacked by these mechanized fish. Kaori immediately sets out on an perilous voyage to find out what happened to Tadashi, helped by Shirakawa — a videographer in search of the truth behind all this...

The story centers on the growth and paths in life of Nikuko and Kikuko, a mother and daughter who lives on a boat.