Osananajimi to Sex Friend Keiyaku

Our secret relationship starts now...

I'll be your sex friend because I love you! That's my choice... "You're fine with anyone, right? So... that includes me, too."

Ayane is in love with Hikaru, her childhood friend who's a year younger. But she finds out that he already has a sex friend!!

I won't let her become a real "girlfriend" so easily! I'm not going to give Hikaru up to anyone else! In order to be with Hikaru any way she can, she tries to become his sex friend, too, but...?!

(Source: Shogakukan, translated)