One of my favorite manga series of all time would have to be Ouran High School Host Club. The series follows the story of Haruhi Fujioka, a young girl whose life becomes intertwined with a host club after breaking a vase. While searching for a peaceful place to study, Haruhi discovers the music room where the host club performs their services to their female clients. However, in a clumsy moment, she accidently breaks an antique vase and ends up owing money to club. Since she doesn't have enough money to pay for the vase itself, she has to lend her skills and work for the club to help pay off her debt. As time progresses, her interactions with the host club also turns into several lifelong friendships with the other characters.