Japan, where the "Rusty Wind" that rusts away everything is blowing violently. An unusual monk is trying to pass through the checkpoint by himself. He has a bow on his back, which is weird for a monk. On the other hand, Milo who runs a clinic in the city of Imihama, is secretly doing research on a new medicine to save his older sister Pawoo, who is infected with rust. And the one who appears in front of him is…

The wanted criminal Bisco Akaboshi has launched a mushroom terrorist attack in Imihama, using his bow to make huge mushrooms bloom everywhere. The city is now in total chaos. Bisco has been looking for a doctor who can dispense medicine to save his master Jabi, who is severely ill. Bisco breaks into the clinic and approaches Milo, but Governor Kurokawa’s guards have arrived.

The captain of Imihama Vigilantes launches an intense attack against Bisco all by herself. Meanwhile, Milo learns from Jabi that there’s a legendary miracle medicine called “Rust-Eater”, which can purify any rust. Milo believes that it’s the key to saving his older sister. After the intense battle, Bisco and Milo meet again, and Milo tells Bisco his decision…

To look for the legendary mushroom Rust-Eater, Bisco and Milo headed to the north-east. They meet with their ally, the big crab Actagawa, but Milo struggles with riding training. However, with his kindness, he and Actagawa manage to understand each other. On that night, the two of them are about to spend the night at Nikko War Condolence Shrine. There, they meet again with the girl with jellyfish hair.

Bisco and Milo head towards Calbero Shellfish Sea in order to go to Tohoku. They arrive in “The Town of Iron Man” on their way. This lonely town, where there’s no adult and only kids are living, has been threatened by the violent Flying Pufferfish. Meanwhile, Pawoo, who’s chasing after Bisco and Milo, meets a strange couple on her way.

Based on the info they got at “The Town of Iron Man”, Bisco and Milo travels further to the north. They meet again with Tirol who is about to be frozen to death in Shimobuki Prefecture, where the heavy snow hits. With the help of Tirol, the two of them will soon reach their destination Crying Child Ravine, where they can find Rust-Eater. 为了取得「食锈」，毕斯可和美禄继续往北边前进。他们在被白雪封闭的霜吹县，与差点被冻死的滋露重逢。在滋露的带领下，来到地下铁白桦线的车站「狐坂」，在那里发现列车，但⋯⋯。

In front of Sanzo, Goku received lethal injuries. Blinded with murderous intent to the culprit, Sanzo ran away from the scene to find the person. Gojyo and Hakkai who was left with Goku, took the very slim chance they got and released Goku's Seiten Taisei's power to save him. 两人穿过隧道，来到子哭幽谷，这时出现在他们面前的是，身躯像龙那么大的双头蛇「筒蛇」。随后追着他们的帕乌也在不巧的时机登场，被卷入危险之中，两人与筒蛇进行一场激战。

Bisco is severely injured after Kurokawa shot him with a rust bullet. To save Pawoo and Jabi who got captured, Milo left Bisco behind and enters the enemy base. Kurokawa has carefully set up a trap for him, and is awaiting. Then, Kurokawa starts to tell Milo about his ambition and the secret of the persecution against Mushroom Guardians. 黑革抢走「食锈」，更抓住帕乌与贾维。为了救出她们两人，美禄单枪匹马前往驻扎地，但面对黑革压倒性的力量，他完全束手无策。黑革开始对伤痕累累的美禄诉说自己的过去，以及蕈菇守护者的秘密。

Milo got into a difficult situation due to Kurokawa’s trap. Jabi got captured by Kurokawa again. Kurokawa boasts to him about his terrifying plan. He plans to make use of “Iron Man”, the defensive weapon that’s considered to have spread “Rusty Wind” all over Japan. In this hopeless situation where nobody seems to be able to stop Kurokawa, someone appears in front of Kurokawa… 毕斯可和美禄中了黑革的陷阱，身受重伤。贾维也再度被抓。黑革对贾维说出自己的野心，并让他见识自己骇人计画的一隅。正当所有人认为没有人能阻止黑

After killing Kurokawa, Bisco sank into the furnace of “Iron Man” and passed away too. The furnace goes out of control, while Milo finally escaped from the dome. However, their next challenge comes immediately, leaving them no time to be sad and mourn for losing Bisco. Now that Bisco has passed away, Milo, who was left behind, starts to ask himself what he can do.

The revived Iron Ttitan proceed to destroy everything one after another. If this continues, Japan will be swallowed by rust again… Milo, who has inherited Bisco's spirit, boldly stands up against Iron Titan. He cooperates with Jabi, Pawoo and Tirol, who rushes to the scene, to hunt down the rampaging Iron Titan… 复活的铁人接二连三破坏城镇。再这样下去，日本会再次被锈蚀吞噬⋯美禄继承了毕斯可灵魂，就像毕斯可那般勇敢地阻挡在铁人面前。贾维、帕乌、滋露也同心协力，努力逼退铁人，但⋯⋯

The Iron Titan advances towards Imihama. Milo repeatedly fights off its intense attacks, while getting seriously injured, in an attempt to stop its invasion. However, just as Milo is about to run out of strength, Bisco is revived from within the Iron Titan. With Bisco and Milo together, the final battle against Iron Titan finally begins! 铁人朝着忌滨前进。美禄已经承受它好几次的攻击，尽管全身受创，依旧试图阻止铁人的猛攻。当他快被杀死的前一刻，毕斯可从铁人当中复活。毕斯可和美禄两人联手，展开与铁人的最终决战！