Shitsu Rakuen Karuta

"The one who came to greet me in my final moments was a pure white grim reaper..."
She speaks of ancient tales akin to the Arabian Nights.

The protagonist, Shatarou, suffers from insomnia, spending each night unable to sleep. Suddenly, a pure white girl, a 'shinigami,' appears before him. She promises to tell him ancient tales every night until he can fall asleep again... But these tales reveal the sins and punishments he has committed.

Until his anger subsides, she continues to speak.
Until his sins are purified, until this body is cleansed...
Until "you" can forgive him.