Nee Ore no Koto, Mada Nakimushi da to Omotteru?

The protagonist Rin was confessed to by her crybaby childhood friend Ryouka.
"When we grow up, I want you to become my wife!!"

However, she rebukes him. "You're a crybaby, so NO WAY!"

After which she makes a promise...
"If you can become strong enough to make me cry instead... I'll become your wife."

Rin ends up moving away after that, and the two childhood friends are separated for over 10 years...

One day, however, just after Rin breaks up with her boyfriend (coincidence???),
they make contact with one another resulting in Ryouka staying over at her place for the night...?

"Hey, Rin... do you remember the promise you made me?"

... ... ... ... ... ... ... ... ...

Still thinking of Ryouka as the crybaby she knew when they were young,
Ryouka totally and utterly melts her heart with his sexual technique.

He's been waiting over 10 years for this day... and the unprepared Rin is like putty in his hands...

(Source: DLsite garumani)