Prince of the Land of Light is a Manga/Manhwa/Manhua in english language, Adventure series, english chapters have been translated and you can read them here. You are reading chapters on the fastest updating comic site. The Summary is

"From a 55-year-old doctor... to an insanely cute 5-year-old prince?!" When Lillias, the youngest prince of the Ashaheim Empire, falls into a lake, he suddenly regains memories of his previous life. In that past life, he was a doctor who saved countless lives-- Now, with the blessing of Lu, the revered Spirit of Light, his new life in the empire begins...!