Baka to Test to Shoukanjuu‎ - Volume 6.5, Me and the Seaside and the Festival Uproar (First Half)

When he did not know her true identity, he treated her very badly, he disliked her too much, she was not elegant enough, she was in the way...Only later did he realize that the woman was his legal wife! He repented, tried to recover her feelings, but she was determined to divorce him.

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Noah Brown had a gift for fighting. Unfortunately punching things didn't pay the bills, at least until he died and an Eldritch god found his soul. The encounter led him to a new world, summoned by bloody cultists, with nothing but the shirt on his back, and a strange item in his system menu.

[???] : A source of infinite potential.

Perhaps he'd finally get to put his gifts to good use.

In a world where humanity struggles to survive against rampaging beasts, Reid Fletcher, once a member of the powerful Fletcher family, has been cast out and abandoned. Born with pitifully low soul power, Reid’s future seemed doomed in a society that values strength above all else. Forced to live in the scrapyards, a forgotten wasteland where the outcasts scavenge and survive, Reid discovers a hidden potential—an ancient artifact known as the Evolution Codex. Read to find out how Reid's journey will unfold. Will he rise to the top or remain a nobody forever?