Hey Spoiler! I do own the "uncut" Japanese dvd, and owned its previous (long out of print) vhs release, as well as seeing it broadcast on HBO as far back as 1981, and have never even seen or heard of that addition to the ending! It's no secret that additional "sex & gore" scenes were shot to "spice" the film up, so I guess it's not impossible that the scene was once part of the film's assembly (just a part I was never aware of)

Bryan