Shitamachi Rocket

Kouhei Tsukuda is a former researcher for the Japan Aerospace Exploration Agency and now owns Tsukuda Factory, a factory left behind by his father in a downtown neighborhood. The Tsukuda Factory continues to fare well, providing valve systems developed in-house to Teikoku Heavy Industries and their strictly domestic Stardust Project rocket development plan. Tsukuda is shocked after Teikoku Heavy Industries changes presidents, and Michio Zaizen tells him the Stardust Project will likely be canceled. To make matters worse, an agricultural tools producer and major client reduce their order for small engines. The future of Tsukuda Factory is thrown into question, and a crisis takes hold as cost concerns begin to overwhelm their ability to produce capable technology.

Tsukuda goes to Tonomura's home and dreams up the development of a new transmission engine. Tsukuda Factory appears to be doing well and wins the Gear Ghost Competition with their Omori Valve, but after Kay Machinery accuses Gear Ghost of patent infringement, news of the competition is overshadowed. Kyoichi Nakagawa, a lawyer with a fateful connection to Tsukuda Factory, approached Kay Machinery and brought the patent infringement to light. Tsukuda consults with his corporate lawyer and receives an unexpected response. Tsukuda Factory decides to cooperate fully with Gear Ghost but suffers repeated setbacks, and a glum atmosphere settles over the company. Can Gear Ghost evade the patent infringement accusations?

The development of the new valve system proceeds smoothly with the help of Gear Ghost, and the only obstacle remaining is the final combustion experiment. Shigeharu Suibara of Teikoku Heavy Industries summons Tsukuda and tells him his company is subject to a credit inquiry. He is told the reason behind this is the acquisition of Gear Ghost. Tonomura is leaving his home on the day of the credit inquiry when his father collapses and requires emergency surgery. With Tonomura absent from the meeting, the Tsukuda Factory members sit crammed in the credit examination office of Teikoku Heavy Industries without the necessary documents. How will they get out of this predicament?

Tsukuda Factory manages to clear the credit inquiry by Teikoku Heavy Industries and begin moving to acquire Gear Ghost in earnest. At this point, the lawyer Kamiya calls and informs them Gear Ghost development information may have been leaked to outside parties. A patent infringement lawsuit ensues, and the members of Tsukuda Factory struggle to come up with a solution. Itami and Shimazu are unable to conceal their shock after unexpectedly discovering a betrayer in their midst. Tonomura makes a serious decision while spending the weekend helping on his family farm.

The patent infringement lawsuit filed by Tsukuda Factory and Gear Ghost against Kay Machinery finally moves forward, and they confront their nemesis Nakagawa directly. Tonomura, who has decided to retire, and the other employees watch with anticipation for the fateful judgment. Zaizen is instructed to leave the Stardust Project and joins a department for new business development related to rockets. Somehow, Zaizen finds himself harvesting rice with Tonomura and other members of Tsukuda Factory and realizes what is truly important.

Shimazu tells Tsukuda and the others that Gear Ghost and Daedalus are in a joint capital venture. They hurry to see Itami, but he is consumed with the desire for revenge against Matoba and forgets his obligation to Tsukuda Factory. Matoba denounces Tsukuda Factory, and Tsukuda is exasperated, but Itami is unmoved. Zaizen visits Tsukuda and reveals his intention to develop an unmanned agricultural robot to save Japanese agriculture from the severe labor shortage brought on by its aging population. Zaizen wants Tsukuda Factory to supply the newly developed engines and transmissions for agricultural tools made by Teikoku Heavy Industries. Zaizen is collaborating with Hirofumi Nogi, a leading researcher of unmanned agricultural robots and professor at Hokkaido Agricultural University.