I'm not entirely sure as I haven't read it specifically. But generally, in this kind of 'isekai' (another world) themed web novel, it might be about a 'yankee' (which could refer to a certain type of character, perhaps a tough or delinquent - like one) who gets transported to another world and is loved by spirits there.
There are several web novels that share some elements. 'Re:Zero − Starting Life in Another World' is somewhat similar in the sense that the main character is in an isekai setting. Although the character isn't a 'yankee' type, the theme of facing challenges and forming relationships in a new world is there. Also, 'Sword Art Online' has an element of being in a different world (virtual in this case) and dealing with different entities, which could be related to the overall theme of the given web novel.
The 'Team Yankee Novel' is mainly about military operations and the experiences of the soldiers. It often depicts combat scenarios, military strategies, and the camaraderie within the military units. It gives readers a look into the world of military warfare and the challenges faced by those on the front lines.
The Team Yankee novel is grounded in a speculative scenario of a large-scale military conflict. It imagines a different outcome and course of events compared to real history.
Yankee Doodle has a long history. It originated as a British song used to mock colonial Americans, but Americans reclaimed it and made it their own during the Revolutionary War.
One popular Yankee ghost story is the tale of the Headless Horseman in Sleepy Hollow. It's about a headless figure on horseback that haunts the area. Another could be the stories of haunted lighthouses along the New England coast, where the ghosts of former lighthouse keepers are said to still be on duty.