*_to_* (cheek_to_cheek, forehead_to_forehead, mouth_to_mouth_feeding, ...)
*-to-* (back-to-back, face-to-face, left-to-right_manga, right-to-left_comic)
Is there one style we can go with? The latter has only those four tags, while the former has many more (even excluding stuff like listening_to_music). If aliasing to the latter, there's the question of where to draw the line...
Updated by jxh2154