Bombastic Sisters 2 Baku Ane 2: Otouto Ippai Shibocchau zo! The Animation

The protagonist and his lover want to have their first time together, but due to past trauma, he can't go any further. The elder sister of the Takesaka household notices his problem and wants to help him... with sexual lessons! Even his cousin and the one who caused his trauma join the party, and the battle of the best sexual lesson begins.