 If you liked
Hayate no Gotoku!
|
 ...then you might like
Nisekoi
|
Although they have different premises, both series follows a main male character where their complicated circumstances lands them in a relationship with another girl (although of different nature). Both series' main female protagonist possesses a stubborn personality when it comes to love but deep down has has genuine feelings for the MC. Throughout both series, we also find out a bit more about some of the other characters that they come in contact with. There are also secrets that unfolds as both series' stories focuses on relationships to tests the potentials for our main characters.
The plot and the length are probably very similar.
Both series are school rom-com harems, have a tsundere from a rich family group as a main female lead, involving promises, misunderstandings, and yakuza in the start of both series, and the most essential part : the plots of both series are driven by the mystery of some jewel/key necklaces.
If you are seeking for long-running harem series that have many cute facial expressions, you might love both of the series.