The protagonist, Tooru Seo, keeps a track of his overflowing delusions on his [Fetish Diary].
One day Tooru forgot said Diary in the classroom so he hurried back to pick it up, but what he found was his classmate Ootori Chikage masturbating while reading his diary.
"Is this wonderful diary yours? If so, I have a proposal for you..."
Turns out that she draws eromanga, but lately she's been in a slump, that’s why she asks Tooru permission to use his diary as inspiration for her work.
"If you cooperate with me, all those naughty things written on the diary, I'll make them come true"
That condition was fascinating, but unrelated to that, Tooru was happy for being praised for his peculiar habit so he accepts helping Chikage.
"Hehe I'm so glad. then, let's do it... right now♪"
Saying so, Chikage pushed down Tooru and she began to fulfill her part of the deal.
In the middle of the act, Chikage realized that both their minds and bodies were perfectly compatible with each other's, so she suddenly confessed her feelings to Tooru.
"Somehow, seems like I've fallen for you... I love you, Tooru. I want you to be mine"
In the end Chikage allowed the confused Tooru to give his answer later, soon after, a close friend of Tooru, Rindou Nao, noticed certain change in him.
Nao, who knew the situation, thought of taking Tooru away from Chikage, leading to her hidden feelings for him to overflow.
"I'm always telling you, but you never take me seriously... I, I love you Tooru-kun"
Out of nowhere, Tooru got confessed by two beautiful girls. Then, both girls began a radical and naughty approach to him.
Furthermore, even his childhood friend Tokitou Rino who loves and sees him as an elder brother comes along, leading to an even more chaotic situation.
"You know, Rino as well, loves you so much, Nii-san! So, let's drown ourselves into pleasure and lust♪"
Tooru, who thought nobody ever would accept his secret habit, was suddenly surrounded by a harem who honestly understand him. Now, his normal daily life turned into a "Real Eroge"