My Friend's Little Sister Has It In for Me!

For high schooler Akiteru Oboshi, the whole youthful experience—fun, friendships, and even having a girlfriend—is a complete waste of time. So when his best friend's sister, Iroha Kohinata, keeps teasing him, Akiteru naturally finds it irritating. She practically lives in his room, always on his bed, a raging storm of clinginess. Why is she only annoying around him?!