Once the artist becomes adept at the basics of drawing manga and anime characters they soon discover that bringing emotions to their characters is more difficult that it seems. Basically to make an anime or hentai character show emotion you only have their facial expressions to do this with. A change in eyebrow height and positioning combined with change in their eyes and mouths are the basic tools to creating emotions in your characters. In typical mangas there are only four basic emotional expressions for the characters: normal (neutral), disappointment, angry, and calm. But in hentai there are three additional basic expressions of emotion: apprehension, lust, and extreme sexual satisfaction.
Because the basic theme of all hentai productions is sex (the word means ‘sexual perversion’ in Japanese) conveying sexual excitement is critical for the believability of the story. Depending on the type of hentai the story is about, how the artist has the characters display their emotions is critical.
In a futanari (dickgirls) based story, the main character is typically a dickgirl who is placed in an all girls institution or situation and is attempting to conceal her condition while becoming aroused by the females around her. She must first look apprehensive then embarrassed and finally sexually aroused as the storyline unfolds around her.
In a lolicon (attraction to female prepubescent child like girls) the main characters must show coy innocence and then wonderment at what they are getting themselves into.
For furry based stories (human like creatures with certain animal characteristic such as a tail or ears) the main characters must convey a sense of mischievousness and a pixie like sense of humor.
Many Japanese hentai artists are helped by certain accepted cultural depictions that are emotional signals to their audience. A large tear shaped drop of water on the forehead displays pique, while a four sided black cross on the forehead signifies anger.