Magic Maker: Isekai Mahou no Tsukurikata

A 30-year-old man who dreams of becoming a wizard suddenly loses his life. Reincarnated in another world as a young child named Shion, he grows up alongside Marie, his dependable older sister who adores him. Shion eagerly anticipates using magical powers, but he discovers that the new world seemingly does not have any magic. He spends the ensuing years as a gloomy and dejected child until a mystical phenomenon at a nearby lake catches the siblings' attention and breathes life back into his magical dream.

While experimenting on the peculiar light emanating from the water, Shion finally confirms that magical energy really exists. It may not be convenient for anything just yet, but Shion devotes his time to studying the anomaly, determined to uncover all the existing wonders in his quest to make magic.