The protagonist, who has been reincarnated in a different world, raises his twin sister using the knowledge from his previous life. Initially, they can't even communicate, but the protagonist studies hard and does his best. The sister, a genius beauty, grows at an incredible pace. However, her love for her brother escalates even more. Will the protagonist be able to guide his sister in the right direction? This story will be told in detail from when she is 0 years old, with a focus on the protagonist's struggles. By the way, the brother is also growing in a rather unusual direction.