DT Tensei: 30-sai Made Doutei de Ten shitara, Shijou Saikyou no Mahoutsukai ni Narimashita!

Amatsuka Kouta, a 30-year-old convenience store clerk who has never had a girlfriend, is reincarnated in another world after being hit by a car. Midland regularly summons people from other worlds, searching for a savior with powerful "magi." Kouta was initially thought to be the weakest person summoned, but when he turns age 30 while still a virgin, his "magi" suddenly awakens. Kouta discovers that he has the same "magi" as the legendary wizard Lord Astron, after he ends up living with the Archibald family, an aristocrat in a remote area…

(Source: Natalie, translated)