Studying in a group with Tsubaki is so sexual that it's terrifying

Studying with her lewd cousin Tsubaki. I returned to my hometown to spend the summer with my family and met my cousin Tsubaki again. She is one year older than me and has more knowledge, so my mother asked Tsubaki to teach me more during this summer vacation. And not only did she teach me knowledge from books, but Tsubaki also wanted to teach me how to make love. She was so lustful, something I couldn't imagine, because of her beauty, I had incest with my cousin.