Nishizawa Kazuki is the younger brother of Ayumu and a friend of Wataru. A year ago, Kazuki met Nagi who was trying to get a balloon which was stuck in a tree and fell in love with her at first sight. When he met her again in Wataru's store he invited her to a walk and finally confessed his love to her.  ~!During their &quot;date&quot; she told she already loves someone and after Hayate saving her from falling in a lake Kazuki realized it was him she loves.!~    - Wiki

The second season of Hayate no Gotoku!. 
 
Ever since he first met Nagi Sanzenin, Hayate Ayasaki's life has become increasingly more crazed and chaotic. Which is a bit of a problem, since, as the eccentric heiress' butler/personal bodyguard, he's theoretically supposed to be a stabilizing and protective influence. Unfortunately, Nagi and her friends attract trouble the way dropped lollipops attract dirt, and if Hayate has to take a couple of nasty licks along the way, that's just part of the job. The real sucker punch, though, is that Nagi's increasing attraction to Hayate himself is getting precariously close to transforming their professional relationship into something far less professional and much more like a relationship. Is Hayate up for the emotional perils of a round of "upstairs, downstairs"? Or will the purely physical dangers of life on Her Majesty's Domestic Service do him in first? 
 
(Source: Sentai Filmworks)

Hardworking Hayate has a plan to pay back the yakuza—who are now the legal owners of his body parts: he’ll kidnap someone and ransom them for a mountain of money! But things get tricky when his would-be kidnappee—who as luck would have it is the daughter of a mind-bogglingly wealthy family—mistakes Hayate’s actions for a confession of love, and subsequently hires him to be her personal servant. At least his employment future is secure, or so he thinks…
 
(Source: Viz Media)

Kazuki Nishizawa