Baku Ane: Otouto Shibocchau zo! The Animation Season 1

A soccer player returns to his parents’ house after training in another city for a few months and getting injured in the process. Luckily, he has four older sisters waiting for him back home, aching to bring him back to full form however they can!

Our protagonist, Takesaka Munetaka, fails the first time he tries having sex with his lover due to trauma he experienced in the past. His sister Ritsuka and his cousin Momotani Mashiro literally put their bodies on the line to give him "sex lessons" and help him recover from his trauma. However, his other sister, Wakana, who gave him his trauma in the first place, joins the fray and the lessons become more than just lessons! Here begins the sisters' war over their little brother!!