"Beyond the Boundary -I'LL BE HERE- Past" is a recap film that condenses the events of the original 12-episode anime series "Beyond the Boundary" into a single narrative. The story is set in a world where supernatural beings known as youmu coexist with humans, often causing harm. The protagonist, Akihito Kanbara, is a high school student who is half-human and half-youmu, granting him immortality and regenerative abilities. Despite his unique nature, Akihito lives an ordinary life until he encounters Mirai Kuriyama, a Spirit World Warrior tasked with hunting youmu.

Mirai wields a blood-manipulating ability, which she uses to combat youmu, but her powers come at a cost, as they drain her own life force. Initially, Mirai attempts to kill Akihito, believing him to be a dangerous youmu. However, after realizing his true nature, she hesitates, and the two form an unlikely bond. As they grow closer, they uncover deeper mysteries surrounding the youmu and the Spirit World Warriors. Akihito’s immortality becomes a focal point, as it ties into the origins of the youmu and the conflicts within their world.

The narrative explores themes of identity, sacrifice, and the blurred lines between humanity and monstrosity. Akihito’s struggle with his dual nature and Mirai’s internal conflict over her duty and her growing feelings for Akihito drive much of the emotional tension. Supporting characters, such as Hiroomi Nase and Mitsuki Nase, add depth to the story, providing both comedic relief and insight into the broader conflicts within the Spirit World Warrior community.

The recap film retains the core elements of the original series, focusing on the evolving relationship between Akihito and Mirai, the battles against powerful youmu, and the eventual confrontation with the Hollow Shadow, a catastrophic entity threatening their world. The film streamlines the plot, emphasizing key moments and character development while maintaining the emotional and thematic weight of the original story.