Yuuki Nishi spends every day walking a line between life and death. He balances just above water, always mere moments from being eaten by sharks. Akira Itou is also walking the same line. He travels across a perilous wire, suspended dozens of feet above a cavern of icy blades. The day the two meet, death seems imminent, for how can the two pass each other without falling to their doom?

Nishi and Itou are both regular players of the solo "White Line Game," and every day they meet. Supporting each other, they are able to successfully grow in skill and continue on their individual quests. But the more their shared path brings them together, the more frustrated Itou grows. They only ever meet during this game of theirs, and though it brings him happiness, Itou longs for more of the child-like Nishi. After being kissed by Nishi, Itou becomes so embarrassed that he feeds Nishi to the sharks. With regret in his heart, he is convinced that his one-sided crush now hates him.

Nishi, however, has only one regret about the encounter—and that is the sudden disappearance of Itou. When the two make amends, their perilous surroundings change and set them up to walk the white line together for the rest of their lives.