Love Hina

Volume 1
Keitaro Urashima is the only boy living at the Hinata House, an all-girl dorm. Despite the fact that he's kind of a screw-up, the girls are climbing all over each other in an effort to tear his clothes off. But it's not what he thinks! Supposedly somewhere on his body is a map to Hinata's secret treasure!
Volume 2
When a crazy robot that looks exactly like Keitaro appears out of the blue at the Hinata House, the tenants of the all-girl dorm band together to fend off the out-of-control "Mecha-Keitaro."