A boy seeking his sister's killer makes a bargain with a stranded magician, pulling his friend into a conflict whose magical rules may decide the world's fate.
Mahiro wants Hakaze's help with a private murder; Hakaze needs someone able to act beyond the island where she has been abandoned. Yoshino joins their uneven alliance carrying a connection to the dead girl that his friend does not fully understand. Personal grief and large-scale catastrophe become difficult to separate.
The bargain works because each participant lacks something the other can supply. Hakaze has knowledge and power but cannot simply leave her island; Mahiro can move through the outside world but cannot solve his sister's murder alone. Yoshino's position beside them makes trust another variable rather than an automatic condition of friendship. The ensemble lead places the boys between larger character portraits, and the separate island frame gives Hakaze's constraint a physical setting. Follow the24 television episodes in sequence. The mystery depends on who knows which part of the past, so its later explanations are not useful preparation for beginning.