After you die, a mysterious entity appears before you with a deal: Continue on your way and go to the afterlife, or be forgotten and live again.
If you decide to accept the deal, you will become a "Guide to the afterlife", and a new life will begin alongside others who also accepted the deal.
Basically 90% of the girls in the city are a love interest for you, not to mention your teammates. As you improve your relationship with your teammates they will be able to remember more about their past life, unlocking new events, new activities and more.