I’ve got the beautiful sample model from one of hentai game, here some of the picture:

well when u see it, there are outline border (silhouette)  in black~ thats what it call cellshade usage in the model above. What is surprising about this cell usage is, there doesn’t need special texture or coding for applied at the model above~ here the sequence of the research:

1 : here i highlight the outline that is cellshade~

2 : The cellshade can be move manually! by moving the outline to the side of character.   So to be conclude, the cellshade using model polygon for the outline but the face have flip to inner model

3 : So to see the exact face model, i flip the face outward~ and u see the result of the cellshade, it only use same model of the character but have little more size from the original ^_^

Creative way of usage~ but maybe kill me when applying bone for both model, character and cellshade ~_~