Well, without having read 'mamoru kun ni megami no shukufuku wo light novel', we can only make assumptions from the title. 'Mamoru kun' might be the main character, and 'megami no shukufuku' which means 'the goddess' blessing' could be the central theme. It could be a story of how this blessing impacts Mamoru kun's life. It might be a fantasy story where the goddess' blessing gives him some special powers or a new purpose in a magical or fictional realm.
You can try to look for it in some specialized Japanese bookstores, both physical and online ones. Some popular online platforms for Japanese light novels might also have it.
Hanako-kun's story in the manga was full of twists and turns. He encountered new friends and enemies, and his powers evolved as he took on more difficult tasks.