From this manga's eManga page:

Gen Tsukiomi appears to be a normal high school student but there is more to him than meets the eye. So when his old caretaker asks him for help in protecting his current charge, Hikari Kuze, Gen wonders what is going on. Besides being a ditzy junior high school student, is Hikari like Gen, with a secret of her own? In what often feels like a comedy of errors, Gen tries to figure out who is after them while struggling to maintain his quickly dwindling control over the situation. As if that wasn't enough, a new romantic rival appears! But which one of them is he actually after?