When I Was Stitching up Corpses in the Funeral Parlor, I Found All the Dead People

I am an embalmer and I have never seen such a strange corpse in my ten years of work. Every deceased person had the same smile on their face, as if they had seen the paradise world. The police determined that it was a natural death until I found Master's ID card in the mouth of the last corpse. After further investigation, I found out that Master had passed away three years ago. Then who has been teaching me my craft every day for the past three years? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.