The Unfortunate Old Man’s Unsurpassable Barrier Magic

The barrier mage’s job is done, right? Then, why not join the Kingdom’s Royal Mage Corps?”
For the last 30 years, a protective barrier shielded the kingdom from the Demon King’s forces. Initially maintained by a hundred barrier mages, their numbers dwindled until only one, Blake, was left to uphold it. At last, came the day when a hero defeated the Demon King. But, in this peaceful world, barrier mages were now considered “useless”— a bottom-rung job with no real purpose.
Blake was at a loss on what to do until he received an unexpected invitation to the capital from said hero. Alice, the Hero who he once saved, encouraged him to join an elite squad reserved for only the best in the kingdom. She insisted that, if he could prove his worth, even those who doubted him would have to yield.
“Barrier mages are useless!”
“Then, all he needs to do is show his strength, right?”
The story unfolds as this underestimated middle-aged man, unaware of his unparalleled skills, wields and strengthens his barrier magic! The tale of a fantasy hero’s rise in another world begins here!