The Yakyuken Special was not alone. The PS1 had a notable niche of "adult" or "ero" games, though Sony’s strict policies kept explicit content limited. Compare:
It is generally not considered a "good" game in a traditional sense. It is mostly sought after today by retro collectors or those interested in the history of obscure Japanese PS1 imports Accessibility: the yakyuken special ps1 rom
The request specifically references the "ROM" (Read-Only Memory) file, which refers to the digital dump of the game disc required for emulation. The Yakyuken Special was not alone