Moto Saikyou Tansakusha no Ojisan. Bishoujo Haishinsha wo Tasukete Oobazuri shiteshimatta

A middle-aged man who's just been fired from his job heads into a dungeon to hunt monsters in order to make a living. There, he saves a beautiful high school girl who works as a dungeon livestreamer. Aiming to boost her viewer count, she recognizes his impressive hunting skills and proposes that they team up. Together, the two set out to create even more thrilling and exciting dungeon footage, but... (Source: Kadokawa, translated)