Majimoji Rurumo

Shibaki is a high-school boy whose only interest is girls. It's just that he's been branded as the greatest pervert at school and the girls avoid him like the plague. 
One day he happens to find a book in the library about how to summon witches. He tries it as a joke, but it turns out to be the real thing. An apprentice witch named Rurumo grants his foolish wish for a high price. Shibaki ends up helping Rurumo and in return she refuses to take his soul. Doing so, Rurumo loses her position and puts her own life on the line. 
Rurumo must complete the task of getting Shibaki to use 666 magic wishing tickets before she can become a witch again. However, every time ticket is used, Shibaki's life shortens. 

Now, Shibaki has his own life on his hands. Make a lot of wishes and help Rurumo become a witch again or resist the temptation and try to live long life.