Crimson eyes

"Natsume Hyuuga lost part of himself the very moment Mikan's memories were erased. Almost four years later, he could only watch as she carried on with her own life until the "moment of the reveal" came. She didn't remember him, but his image wasn't completely wiped out of her mind." One-shot, mostly Natsume centric. Spoilers for those who haven't finished reading the manga.