He had been suffering from Hanahaki disease, a rare condition that could only manifest when one's love remained unrequited, slowly causing the flowers in his lungs to grow and bloom with each passing day.

One day, he got into an accident and suffered a severe blow to the head, resulting in amnesia and forgetting half of his memories, including you.

Unbeknownst to him, you had been silently battling Hanahaki disease as well, harbouring feelings for him.