Hanayome wo Ryakudatsu Sareta Ore wa, Tada Heion ni Kurashitai.

"Would I not be a suitable replacement for my sister?" "Wait just a moment—this wedding is officially off!" What was meant to be the happiest day of Shin's life turns into a public spectacle of humiliation. Standing at the altar as the groom, he watches in disbelief as his bride is brazenly stolen away right before the eyes of a massive gathering of guests. The ceremony collapses into chaos, leaving him abandoned and utterly bewildered by the sudden destruction of his future. Exhausted and emotionally drained from the ordeal, Shin retreats to his home, hoping only for quiet solitude. However, the very next morning brings an unexpected visitor to his doorstep: Nene, the younger sister of his runaway fiancée. Rather than bringing further complications, she arrives with a singular, earnest desire to take her sister's place and care for him. Before Shin can fully process the whirlwind of events, he finds himself swept into an entirely different kind of reality. Instead of mourning his ruined wedding, he is suddenly enveloped in Nene's unwavering affection. What begins as a devastating public betrayal gradually transforms into a surprisingly tender domestic life, where Shin is constantly doted upon and indulged by the devoted younger sister who refuses to let him suffer alone.