The Protagonist Is Attacked by a Common Ex-Boyfriend, but the Mecha Master

The walking humanoid weapon, the cool guy Shouhe who is MVP in both intelligence and force, has not yet thought about his attributes. Dressed as the protagonist and attacked the same ex-boyfriend, but they both became my little brother (confirmed) A long story about fighting monsters and upgrading the mecha with passion (sure) Intention: Self-reliance and self-reliance