Ero h manga often contains adult content and more explicit themes compared to regular manga which might focus on a wider range of subjects without such explicit elements.
For some, it might be the unique art style or the diverse storylines. It can offer a form of escape or entertainment that clicks with their preferences.
Hard to say. You'd have to look closely at the story and the interactions between the characters to determine if that's the case. Maybe there are clues or indications throughout the manga that would clarify it.
My answer may confuse you. I understand that Battle Through the Heavens manga is different from the novel. The manga doesn't contain the H plot in the novel. The production and modification of the manga depended on the manga company's creative intentions and storyline. Whether or not the manga about the relationship between Xiao Yan and Medusa would draw this part depended on the manga company's arrangements and creative intentions. I hope my answer can help you.
I haven't read about the Battle Through the Heavens manga. H elements were usually used in comics to describe sexual elements to enhance the emotions and atmosphere of the story. The novel Battle Through the Heavens has also been adapted into various forms such as manga and animation. I'm not sure if there are specific rules or restrictions for the H element. You are advised to check the manga or related publishing or copyright information to find out if there are specific H element regulations.