Magic Maker: Isekai Mahou no Tsukurikata

On the night of his 30th birthday, one man’s dreams of wielding magic come true after he unexpectedly passes away. He wakes as Sion, a young child in another world. He and his elder sister, Marie, are the children of a lower-class noble family who govern their region. After receiving conflicting messages from their father, Sion and Marie set out on an adventure to uncover the magic.

(Source: Crunchyroll)