On the eve of his 17th birthday, Yotsuba Mitsuru endures his 30th breakup. Reflecting on a decade-old pact with his birthday twin and best friend, he ventures to the park for a reunion. However, a mysterious light interrupts his quest, rendering him unconscious just as he glimpses his companion. Upon regaining consciousness in the hospital, Mitsuru learns that fate has granted him a rare opportunity for a fresh start, albeit with unforeseen conditions.