From KodanClub:
Chiya Minakami lived the life of a saint. Until her death at 92, she was dedicated to the care of children inflicted with serious disease. Convinced that she had done enough to go straight to heaven, she is surprised by the Prince of Hades. "How can you expect to have enough experience of love when you remained a virgin all your life? We shall give you the body of an 18-year-old girl and dispatch you to 'Chichonmanchi' -- our pleasure hell -- where you may learn something about loving." Chiya is thus given a young and voluptuous body and sent to the strange, magical home of weird beasts and erotic flora. Her flesh may be young, but her mind remains old, stubborn and guided by nineteenth-century morality. "How disgusting! One is not amused by this place." Can Chiya pass the entrance test to heaven? A sex comedy like nothing you have seen before.

The series was reprinted in 2004, 2 in 1 volumes, and renamed "Tengoku he no kaidan".