Earl Grey (Author)

The protagonist, who has accidentally acquired a bizarre manhood, is sobbing because even prostit**es are running away from him. But one day, he receives an order from his father, the king. The order is: “Conquer Avalon’s dungeon!”. In that dungeon, created by an ancient mage, may lie the hidden treasure that will restore his manhood!…

A classic take on yandere stories. This depicts the events of what happens after a brother “betrays” his sister.