Love Hina

When Keitaro Urashima fails his entrance exams to get into Tokyo University for the second time, he's officially an unemployed and uneducated slacker. To make things worse, his parents have kicked him out of his house. Fortunately, his grandmother owns the fabulous Hinata Lodge and has agreed to take Keitaro in as caretaker. What he doesn't know is that the lodge is actually a girls' dorm and he's the only guy around! Most guys would kill to live with five sexy ladies, but if Keitaro's not careful, this job will kill him.
(Source: Kodansha Comics)