Maou-sama to Shun-kun

One day, a young boy named Shun-kun is picked up at his kindergarten by the actual Demon King!
It seems that the demon king, "Maou-chan", has come to conquer the world, but he seems he also has a soft spot for Shun-kun...?

(Source: Kadokawa, translated)

Note: includes 7 extra chapters.