A young man who should have died in an accident is reborn as Arte, the second son of a powerful marquis family in a world of swords and magic. Surrounded by a loving family, he enjoys a smooth and prosperous life. However, during the selection ceremony to receive magical abilities, he is granted a mysterious innate magic called "Light." While others dismiss it as a "failed" magic, Arte’s past life memories return, revealing the true nature of his magic…!? Using his past life's knowledge, he aims to transform this "failed" magic into the "strongest" magic…!? The strongest and freest adventure of a man known as "Flash" begins now—!