The doujin's title is a dual pun upon the person "Asuna Yuuki" and not just because Zettai Ryouiki is the space between the skirt and tops of thigh-high stockings/leggings, but also because Asuna is the sole heir and user of the nearly deus ex machina skill from the player nicknamed "Absolute Sword". The skill is technically faster than one that can be created and memorized by a player in the game.
Background: Sword Art Online (SAO) is a set of light novels about an ensemble set of characters that meet each other through their participation in online Virtual Reality MMORPG (VRMMORPG) games. As the LNs describe their adventures, this essentially creates a story that includes multiple levels of abstraction since the LN then becomes a fictional story about fictional characters who roleplay fictional characters in a fictional environment.