"I wanna try having sex with a good woman"
That was the protagonist Keiichi's longing. Keiichi has a childhood friend, Haru Momose, who is his only female friend. In any case, this girl has a pretty face.

"If I could do those things with her..."
When he realized it, Keiichi couldn't stop himself from thinking about Haru. In the meantime, Haru suddenly arrives at his house to bring him the wallet he dropped at school. While the two of them were alone in the middle of such an awkward atmosphere, Haru takes some sweets from her bag; In this exact moment Keiichi sees her panties... At last, unable to hold back with his reasoning, he pushes Haru down on the floor.

'This is the first time this has happened to me...'
At first, Haru resists, but Keiichi's cunnilingus quickly brings her to paradise.

"I'm also gonna take off my clothes soon."
And then, what appeared in front of Haru's eyes, beyond her imagination, was Keiichi's huge cock...

'That huge thing is going to tear my crotch!'

(Source: DLsite)

[Note: Each book has 2 near-identical versions, one is a heavily censored softcore version and the hardcore version marked R-18 has mosaics. The covers are slightly different but the story is the same.]