Kubo-san wa Boku (Mobu) wo Yurusanai久保さんは僕(モブ)を許さない

Shiraishi is a plain boy who is two hairs short from being invisible to his classmates and peers; in other words a "mob" character. Cue Kubo, his beautiful next-seat neighbor who always notices him and playfully experiments on him to gauge just how "invisible" he really is... and then she declares herself his "heroine".