Goodbye, Life; Hello, Reclusive Dragon Life

After his life was cut short in the worst way, he can only start over as a dragon. This time, Green wants to live a little longer.

So a dragon in another world must remember four rules: First, don't draw attention to yourself. Second, don't get into trouble. Third, don't steal princesses. Fourth, don't hoard treasure.

To make a living, he should also do good deeds: heal ordinary people afflicted by curses, and incidentally beat up the dragon slayers who came looking for trouble; protect the peace of the great forest, and incidentally beat up the dragon slayers who were starting fires by drilling wood; seal away rampaging ancient weapons, and incidentally beat up the dragon slayers who just happened to pass by; protect the environment and purify the water, and incidentally beat up the dragon slayers who were bathing in the lake and making way too many bubbles...

What is going on? Why are there more and more strange dragon slayers?