Tenchi Muyou! Ryououki
All Tenchi Muyou! Ryououki released episodes
Tenchi Masaki was an ordinary schoolboy training at the Shrine of his family. Descended from a great Warrior who sealed a demon away long ago, Tenchi will one day continue the tradition of guarding the resting place. A pity that he ends up releasing the demon and now its out for revenge on him! But it's...a Beautiful woman? Maybe the trouble to come is not so bad?
The original Harem series that I have been following since a young age. (12 or something.) so I maybe a little bias but it is the greatest harem ever.