Nettori Bakunyuu Mama Yuka ~Musuko no Dokusen Seiyoku ni Sareru ga Mama~

Atsushi was a college student in agony.
Until now it had been just Atsushi and his mother together.
He'd developed a mother complex. She was his alone! But now his step-father was returning home from business...

Atsushi couldn't control his jealousy. He went into a risky relationship with his own mother...

[From DLsite English]