From Useless to Peerless: A Barrier Mage's Journey

Thirty years have passed since the barrier protecting the kingdom from the Demon Lord's army was established. From the initial 100 barrier mages, their numbers dwindled, leaving only Blake to maintain the barrier. Finally, the day arrived when the hero defeated the Demon Lord, but in this newfound peaceful world, "barrier mages are no longer needed," and they're treated as useless, bottom-tier professionals. As Blake was at a loss, a shocking invitation arrived from the hero in the royal capital. Alice, the hero who was once helped by Blake, recommends him to join an elite unit. Despite opposition from those who consider him useless, Alice firmly states that once others see Blake's true worth, they'll understand. "Barrier mages are unnecessary!" "Well then, it's fine if he proves his abilities, right?" Mocked as incompetent, yet unknowingly honing his barrier techniques to perfection, this middle-aged man becomes invincible and unstoppable! The isekai rise-to-power fantasy begins!