Soul Swap with the Demon Lord

Zara Shaw accidentally swaps souls with Demon Lord Silas Voss. Forced to act as the Demon Lord, Zara uses her kind nature to warm the Nether Palace. Silas, in Zara's body, experiences kindness and learns warmth. They work together to fight hostile forces, swap back, and find true love. The soul swap allows the cold Demon Lord to accept warmth, and the junior sister to show courage.