I Am the Mysterious Corpse Collector

In a small courtyard, a mysterious man in black robes said to three identical children in front of him: "When the world's first foul spirit fell into the Mother River, the Mother River truly became a 'mother', but the thing is, the mother's children are not like naughty children, but more like a tsunami sweeping the world." The three children seemed not to understand what the mysterious man in black robe meant, so they asked at the same time: "What does this mean?" The mysterious man in black robe did not answer them, but stared at the three children and said: "Assimilation, evolution, ego, these are the names of the three of you." "Why?" "To... Kill 'Mother'."