Long ago, a goddess descended from Heaven and blessed the desolate land of Gatepia. As a result, gigantic gates appeared, leading to dungeons abundant in kirakuri, crystals containing the energy needed for the foundation of the world. This led to the formation of various companies of adventurers who would harvest kirakuri from the dungeons. Following his father's disappearance inside one of the biggest gates in Gatepia, Minato is urged by his childhood friend Yutoria to become the president of his father's treasure-hunting company—the Kibou Company. He reluctantly agrees and meets with the other employees: the priest Makoto, the soldier Akari, and the accountant Guide. Thus, Minato begins his tenure as president. As he and his comrades strive to fulfill various missions and other assorted tasks in order to keep their small company alive, they will uncover the mystery behind their former leader's sudden departure.

Nagisa is a schoolgirl with schoolgirl tendencies, waking up late, rushing off to school and meeting up with friends upon the way. One morning Nagisa comes across a woman dressed in a strange uniform who seems to stare at her, unnerving Nagisa. Later that day, whilst staring out the window, Nagisa becomes aware of a ball bouncing by itself which flings itself towards her window seat, shattering the glass yet not harming her... Turning back to the front she finds a gaping mouth bristling with teeth inches from her face and no-one else about. She screams and the world returns to normal with her standing and the centre of curiosity of her class... why did she scream?

Dr. Raichii is the only Tsufurujin (the race eradicated by the Saiyajin many years ago) thought to have survived. He now is going to take revenge on the only surviving Saiyajin still alive, Goku and Vegeta. He uses machines that emit destron, a gas that will destroy all life on Earth. Now the the Z warriors only have 72 hours to find and destroy Dr. Raichii. (Source: ANN)

Part II of Sword Gai: The Animation.