“Sabitsuita Ken” wo Tameshi ni Kyoukashite Mitara, Tondemonai Maken ni Bakemashita

In this world, when you turn twelve, God gives you a special weapon called a sacred weapon. Rust, a boy living in a remote village, dreams of becoming an adventurer with his childhood friend Ruby. Ruby receives the highest rank, A, but Rust receives a battered, F-ranked rusty sword.