Hayate the combat butler, vol. 20 (Viz Media)

Poor Hayate Ayasaki is responsible for repaying his parents' 150 million yen debt. One Christmas, he meets a girl named Nagi, and after a series of misunderstandings, he somehow ends up working as her butler. Nagi covers for Hayate's debt, but has Hayate dug himself deeper into a different kind of hole? Wataru and Saki have flown to Vegas on a Golden Week vacation that they can't afford, with the deeply questionable plan of winning the money for a ticket back home. Instead, Saki finds herself playing the Strip's most ruthless card shark - Wataru's reprobate mother - with Wataru as collateral. There's plenty of fear and loathing in Las Vegas tonight, but at least things are going better for Hayate and Nagi, sunning with their friends on the Greek isles. That is, until they stumble into an honest-to-goodness labyrinth...