My parent's remarriage brought me a step-sister two years my junior.

However, ever since she was bullied in middle school, my step-sister had been unable to leave her room.

To get my troubled step-sister to open her heart to me, I, her older brother, went through a process of trial and error. As a result, I was eventually allowed into her room, but...

「――I've become someone who can't live without you, Big Brother♡」

As a result of constantly being by her side and acting as her older brother.

Before I knew it, I found myself spending my days being pursued by an erotic and intense step-sister.

※ The yandere awakening takes a little time. Please enjoy being teased as you read the early chapters.