Imouto ga Brocon de Aru koto wo Ani dake wa Shitteiru.

My little sister loves me so much that it’s scary… no, seriously. My sister—Akari Namiki , is definitely a very charming girl. She’s got wits, she’s got beauty, she’s got style. But just look at me, I’m just some extra-ordinary mob. Now the problem that I’m facing is that this sister of mine loves me way too much. In my third year of middle school, I found the Onii-chan Notes in Akari’s room: a detailed log of my every behavior. Not to mention when she was usually so cold towards me, lo and behold, she was head over heels in her notebook. Oh, let’s not forget, my discovery of finding out that there were surveillance cameras and listening devices hidden around my room…! In the summer of my second year of highschool, I learned of Akari’s plan to ‘Lock up Onii-chan, and make it so he can’t live without me’. I made my decision. Then and there. To interact with Akari as a brother—nothing more—and stop her before this goes too far—!

(Source: Kadokawa Sneaker Bunko, translated)