Here is a little description of each character specifically for this Naruto hentai manga.
He loves Sakura-chan so much; he always follows her with his eyes, he never learns and continues to hit on her. Always trying to get her attention, even when she gets angry. He hates Sasuke and Sai (they hinder him a lot) but the are important too.
She likes Naruto (the likely winner). She isn’t honest with herself and is always hiding true feelings for Naruto and instead of telling him the truth, she claims that she likes Sasuke.
A lot of things happened and he (recently) came back to the leaf village. It seems that he’s knows about Sakura liking Naruto for quite some time. For some reason he’s getting along rather well with the other three characters.
He has read many (unreliable) books about love and feelings between a man and a woman. So now he tries to make Naruto and Sakura’s relationship go smoothly.