Typically, they often have a school - based setting. This allows for a lot of interactions between characters in a relatively closed environment. For example, in 'High School DxD', the school setting is a major part of the story. Another characteristic is the presence of a male protagonist who is usually surrounded by female characters. This creates opportunities for those ecchi moments. In 'To Love - Ru', the male lead is constantly in situations with multiple female characters.
One popular one is 'High School DxD'. It combines elements of action, fantasy, and of course, ecchi. The story follows Issei Hyodo, a perverted high school student who gets killed on his first date and is then revived as a devil. Another is 'To Love -Ru', which has a lot of fan service moments with its harem - like setting and the various female characters.
Another great ecchi light novel is 'To Love - Ru'. It's about an alien girl named Lala who comes to Earth and gets involved with a high school boy named Rito. There are numerous comical and ecchi situations as Rito tries to deal with Lala's advances and the chaos that follows her presence.
A good example is 'Sakura Spirit'. It has an interesting plot along with some ecchi content. The art style is quite appealing. There's also 'HuniePop', which combines dating - sim elements with a bit of ecchi. You get to interact with different characters and the game has a unique gameplay mechanic that ties in with the story and the ecchi aspects.
Another great ecchi harem light novel is 'Date A Live'. Shido has to go on dates with different spirit girls to save the world. There are plenty of fan - service moments and a growing harem around him. The story is also quite engaging as it combines action, romance and the unique concept of dealing with spirits.
Well, 'Haganai: I Don't Have Many Friends' is an ecchi novel worth mentioning. It's about a group of misfits trying to make friends and there are some ecchi - like situations that add a certain charm to the story. 'Kiss x Sis' is also an ecchi - heavy novel, which tells the story of a boy living with his two step - sisters and the various comical and ecchi situations that arise. Additionally, 'Sekirei' is an interesting ecchi novel that combines battles and relationships with a good dose of ecchi content.
One great ecchi anime with a good story is 'High School DxD'. It follows the story of Issei Hyodo, a perverted high school student who gets killed and is then reincarnated as a devil. Alongside the ecchi elements such as the fan service of the female characters in revealing outfits, there is a complex story involving battles between different supernatural factions, Issei's growth as a devil, and his relationships with his friends and love interests.
For beginners, 'The World God Only Knows' is a good start. It has a nice blend of ecchi elements with a plot about a boy who has to 'conquer' girls' hearts. It's not overly explicit but still has that ecchi charm.
'Haganai: I Don't Have Many Friends' is also suitable. It's about a group of loners in high school who form a club. There are some ecchi undertones, especially with the interactions between the male and female characters. It's more about the characters' growth and their attempts at making friends while having some comical and slightly ecchi moments.
I would also recommend 'Katawa Shoujo'. While it does have some ecchi aspects, it is also very much about the characters' growth and relationships. It's a good entry - point as it shows that ecchi visual novels can be more than just about the risqué content. The writing is engaging and the different story paths make it interesting for new players to explore.