Kimi no Mae Dake Onnanoko

Akane spends most of her time in her childhood friend Kouta's room, secretly aware of her feelings for him but unable to confess. Having never had her first sexual experience, she suddenly worries that Kouta might already be a virgin.

Inspired by something Kouta says, she tries to seduce him by showing him her ample breasts. To her surprise, Kouta eagerly grabs her breasts, and she ends up feeling incredibly good. His practiced touch makes her wonder if he's actually experienced, so this time she spreads her legs and tries to seduce him.