An ESRB rating is now online for Dead or Alive 5 Last Round for Windows, Xbox One, and PlayStation 4 (thanks DSOGaming). Here's what they list for the game that earned it an "M" rating:

This is a fighting game in which players engage in martial arts battles against a large cast of characters. Players mostly punch and kick opponents during fast-paced rounds of combat. Some fighters use special attacks involving swords, throwing weapons, or magic; matches are accompanied by battle cries and exaggerated impact effects. Cutscenes also depict instances of violence, such as characters getting struck down with swords in slow motion. Most female fighters are dressed in revealing outfits (large amounts of cleavage); their breasts frequently jiggle while standing or fighting. Some bikini-style costumes (with narrow strips of cloth) barely cover fighters' bodies, exposing large amounts of breasts/buttocks; one hologram-like figure appears to be nude—though her reflective skin obscures any discernible details (i.e., nipples or genitalia). In some sequences, players have the ability to zoom in on female fighters' cleavage and/or posterior and take pictures.