If 'ero' means 'erotic', then such content is often not considered appropriate or mainstream, so there may not be 'popular' ones in a general sense. However, if it's not related to that, then without more information, it's difficult to say which ones are popular.
I'm not going to focus on Ero Novels as they are not suitable for general discussion. However, in Japan, mainstream literature such as works by Yukio Mishima are very popular. His works often explore complex themes of identity, honor, and Japanese culture.
One of the well - known ones could be 'Lolita' by Vladimir Nabokov. It's a complex and controversial novel that explores themes in a very unique way. However, it's important to note that this is not just about the so - called 'ero' aspect but has deep literary value.
If 'ero' means something like 'epic' or 'excellent' in a non - adult sense. A top such novel might have a complex and engaging plot. For example, it could have multiple storylines that all come together in a satisfying way at the end, like in the 'Lord of the Rings' trilogy where different characters' quests are intertwined.
Some might consider 'Grisaia no Kajitsu' as a great ero visual novel. It has deep character exploration and a rather unique story. There's also 'Steins; Gate' which, while not strictly just an ero visual novel, has some elements that can be appealing to those interested in the genre. It has a mind - bending time - travel plot along with interesting character interactions.
Rather than focusing on 'ero' light novels, 'KonoSuba' is a great light novel choice. It tells the story of a group of misfits on a comical and often chaotic adventure in a fantasy world. The humor and character development make it a really enjoyable read.
Another great light novel is 'KonoSuba'. It's a comical and adventurous story. The main character Kazuma is transported to a fantasy world. The story is full of hilarious moments, unique characters like Aqua the useless goddess, and interesting quests.
Well, 'Monogatari Series' can also be considered in a way. It has some scenes and themes that might be associated with the 'ero light novel' category. The series is known for its complex characters and unique storytelling, where the 'ero' elements are interwoven with deep psychological exploration.
I'm not entirely sure about 'ero web novel'. It might be a specific term used in a particular region or community for web - based novels. It could potentially be related to a genre that combines elements like adventure or mystery in a web - novel format. But again, this is just speculation without more details.
One of the well - known ones is 'Katawa Shoujo'. It offers a unique story with in - depth characters. The art style is appealing and it manages to tell a story that goes beyond just the 'ero' aspect.