 Although "seme" and "uke" roles are already used in some manga to describe which member of the relationship is more dominant and which member is more passive, there are just as many manga novels which subtly or overtly differentiate between the two.Anal sex is a prevalent theme in "yaoi", as nearly all stories feature it in some way.The storyline where an "uke" is reluctant to have anal sex with a "seme" is considered to be similar to the reader's reluctance to have sexual contact with someone for the first time.