Her brother was neurotic about his coming exam.
She loved him too much to see him suffer, and let him masturbate to her.
This only added to his stress, since he couldn't be inside her...

Things escalated day by day, until he began stretching her anus.

"Look, oniichan... Look at my gaping asshole. Look how far it opens."

Compassionate, lewd, heartfelt, perverse incest.

[From DLsite English]