Each video in the series has different scenarios but always depicts the wife meeting a black guy and the husband getting a sex tape of them. The ending is always the same. Wife gets creampied.
Wife learns English from a black teacher. Black dude takes her to hotel suite and creampies her. Wife stops going for classes but later ends up wanting some more BBC. Goes to black dude for another sexsion.
WANZ-873 turns things up when Tohno Miho ends up pregnant with the black dude's baby.
All of these movies are genre "cheaing wife" not BBC cuckolding. :-(.
If the husband/boyfriend does not know about the cheating then it is not cuckolding.