Dakara Boku wa, H ga Dekinai.

One day, first-class Grim Reaper Lisara, for her own reasons, secretly enters the human world. After searching in vain for her target, Lisara is completely exhausted. That's when Ryousuke Kaga approaches her. To help Lisara out, he leads her out of the rain and to his cozy home, where he tells her, "I will do anything to help you." When Lisara hears that, she suddenly embraces Ryousuke and...?! (Source: Yen Press)