The mystery dissolves halfway through, but that's the whole point, once you stop waiting for the twist to matter, the actual romances start landing. Shougo's genuinely likable enough that watching him navigate five girls who feel like people instead of stock types becomes the real draw. This OVA is just more of that, which is exactly what the show earned by the time it ended.
Shougo's wild ride continues as he navigates the chaotic aftermath of his father's ridiculous will. The inheritance hunt that forced him into a school full of potential brides has left him tangled up with multiple girls, each one convinced they might be his destined partner. But there's still the nagging problem that lurks underneath every romantic moment: somewhere among these candidates is his actual sister, and neither of them knows who she is. This bonus episode strips away the pretense of plot progression and leans fully into what made the series tick in the first place: pure comedic chaos. The cast bounces off each other with zero shame, the romantic tension gets turned up to absurd levels, and Shougo finds himself in increasingly ridiculous situations that somehow always circle back to the central mystery. If you made it through the TV run enjoying the show's particular brand of harem comedy mixed with genuine confusion and awkwardness, this unaired episode delivers exactly what you came for: more of the same madness, cranked up without any obligation to move the story forward.