Shikizakura: where cherry blossoms are in full bloom while trees are colored with autumn leaves. In this special place, where the transient world meets the spirit world, a ritual to save humanity is about to begin… High school student Kakeru Miwa, by a strange turn of events, winds up being an irregular member of a power suit team tasked with battling Oni. These Oni possess humans and try to cling to the transient world. Only the power suit, Yoroi, which combines ancient secrets with the latest technology, can protect people from Oni. Kakeru decides to become a hero who will battle Oni and protect Ouka Myoujin, the shrine maiden fated with saving the world.
In 2079, the world's first orbital elevator was built in the Pacific Ocean to commemorate the peace that mankind regained after the 3rd World War. However, during the completion ceremony, a huge red humanoid object appears from outer space. It was so powerful that mankind was defeated in vain resistance. The orbital elevator was occupied, and since then mankind has entered a war with the red hostile flying object "Vacant" flying from there. Summer 2099. "It's been 20 years since the war started." Humanity developed the humanoid 7th generation fighter "Seventh" and succeeded in suppressing "Vacant" to the vicinity of the orbital elevator.
2006, Shikoku's shipping city faces the Seto Inland Sea. Akio Hoshigami, a girl who lost her dream of becoming a track and field athlete due to a leg injury, entered high school with her best friend Ayano Umisoe. Club activities and meeting new friends, Meizakura, who was empty, is gradually regaining her former self. However, one day Saiki suddenly disappears. On this planet, there have been battles that have continued since ancient times. Once given to God, eight giants with empty souls "Star Machina".
