The protagonist has been living with his step-sister, who is much older than him, since his parents left home for a long-term overseas assignment.
His step-sister lives alone because she wants to focus on her work, but she supports him and sends him to school.
But one day...

"What? The payments have stopped?"

The protagonist is suddenly kicked out of the school dormitory for non-payment.
He is forced to go to the apartment where his sister lives alone--

"She's dead!!"

He finds his sister collapsed in her underwear for some reason.
But she's not dead.

"No, it's all over now..."

"Sister...?"

His sister is actually a manga artist, and she's in a serious slump.

Because of this, her work has stalled, and her dorm rent payments have stopped.

"Ugh, brother... I can't think of anything..."

"Sis... You've pushed yourself so hard for me..."

The protagonist makes a decision.
He must now support his sister who has been working so hard.
He blurts out the words with that thought.

"Don't worry! I'll help you with anything, even ideas!"

"Really...? Did you just say anything...?"

That statement will greatly change the fate of the brother and sister.
Because the sister is not just a manga artist.

"I've been keeping it a secret up until now... but I support my brother by drawing erotic manga..."

And so, to save his good-for-nothing, perverted sister.
And to create even better erotic manga.
Their innocent yet greedy sex life begins...!!

[Machine translated from https://www.getchu.com/soft.phtml?id=1309732]