Rumor has it that those unwilling to forget their past lives or be reborn jump into the River of Oblivion. If they endure its agony, they can avoid drinking Granny Meng's soup, escape rebirth, and keep their memories of the past.
For some reason, in recent years, the number of ghosts jumping into the River of Oblivion has increased every year. Those who can't endure its agony don't just fail to remain ghosts, they also pollute the river. And even those who can endure it are growing in number, which could cause the river to clog.
So this year, the Underworld established a new task. The King of Hell assigned it to Granny Meng, since she lived nearby and could manage things more conveniently. What was the job? Resolve the obsessions of those who were determined to jump into the river, and convince them to be reborn of their own free will.
Su Meng's newly hired assistant got stuck with the job. Granny Meng couldn't be bothered with it, so she tossed it over to Su Meng. And that's how Su Meng became a cleaner on the River of Oblivion.
