The Infinite Level-up Cheat and the Deadliest Skill

High school student Hayato Katsuragi is reincarnated as Rayvelt Runwalker, the son of an aristocrat from another world, after a traffic accident. At the time of his reincarnation, the goddess bestows upon him a cheat skill with no level limit, but at the same time, he also acquires the most dangerous skill, "One Who Has Been Struck by Difficulties." Condemned to a life on hard mode, Ray decides to undergo intensive training to become stronger. While undergoing training, he lives a happy life surrounded by his cute maid and younger sister, but then a horde of monsters invades...!? (Source: CMOA, translated)