The Hundredfold Haven (Hyakujuu no Ansokusho)

When eighteen-year-old Akira Sakamoto saves a mother and daughter from a speeding car, he is thrust into an alternate reality game by an unknown System. The game known as the Fortress of the Fallen. In the timeless realm of Hyakujuu no Ansokusho, Akira gains power without competition in the tutorial phase, only to be double-crossed by the System, resetting his progress back to his initial stage as he enters the live game. Now, Akira must navigate a treacherous world, uncover the System's dark secrets, and find a way back home. But this time around he isn't alone; with new comrades forge, can he outsmart the game, or will he be trapped forever by the System's machinations? The fate of his reality hangs in the balance.