Isekai Tensei de Kenja ni Natte Boukensha Seikatsu: [Mahou Kairyou] de Isekai Saikyou

After his tragic death, Minato was reborn in a world where Offensive Magic has not been banned. He was thrilled to see that Offensive Magic for the first time, however he couldn't help but wonder why all the magic circles are so inefficient?! After witnessing how ineffective the magic in this new world is, he decides to use knowledge from his previous, far more advanced world to improve it. Come along on Minato's quest to improve the magic of his new home!

(Source: MANGA UP!)