Train (rear-entry chain)

Description: The receiving partner holds all fours while a kneeling partner enters from behind, and a further partner kneels behind that one: the same rear-entry link repeated down a line, every body facing the same direction. The term also covers the sequential practice in which partners take the rear position one after another rather than forming a literal simultaneous chain.

Variations: Group scenes extend the chain with additional same-direction links; the rotation format instead cycles fresh partners through the single rear slot in turn.

On camera: A wide profile is the natural frame; the repeated silhouettes stacked along one axis are what identify the arrangement at a glance.

AI design considerations: Model one rear-entry pair, then duplicate the offset: each added figure copies the same spacing and kneel height down the line. Keep hip-to-hip registration consistent from link to link, or the chain reads as separate couples.