Daichi, who was entering his sophomore year in high school that spring, had concocted a story about having a younger sister solely to initiate a conversation with his crush. However, before he could confess his deceit, a breathtaking stranger addresses him as "Onii-chan" (older brother). Daichi is taken aback as his fictitious sibling becomes a tangible presence, but an even more remarkable occurrence ensues. Without wasting any time, Daichi must discuss matters with his newfound sister first and foremost.
