A Sakadagami (Pali: "once returner") is a holy person in Buddhism and constitutes the second degree of enlightenment. If a Sakadagami dies, he is reborn again as a human being.
In that next life (as a human being) he becomes either Anagami or Arahant. His next life is his last life in the human world, unless in this life he already attains Anagamihood, in which case he will not be reborn as a human being, but as a very high divine being. If he already attains Arahanthood in this life he will not be reborn.
The Sakadagami is the second degree of holiness. The Sakadagami is free from the first three of the ten chains, from which the Sotapanna is also freed.
For the Sakadagami, however, the fourth chain (lust and desire) and the fifth chain (ill will or hatred) are also greatly weakened. Before a person can become a Sakadagami, Sotapannahood must first be attained.