As light as you would expect from the title. Azusa dies from overwork, and is asked what she wants for her next life. Immortality, and a nice quiet life in the mountains, with a near-by village to buy things.
She gets it, and is a witch in world where killing monsters makes them turn into gems. Over the course of three hundred years, she kicks back, sleeps late, studies grimoires to amuse herself, kills slimes -- 2 experience points and 6 copper pieces a piece -- for her modest needs, even when she factors in buying the grimoires, and makes healing potions for the village.
Then, someone notices her level.
Life is no longer so peaceful. It involves a dragon who is the strongest, mushrooms, a protective barrier, a wedding, slime spirits, and more.