Double Christmas Miracle

Teruya Ken'Ichi has a huge crush on his bestfriend. From the day he laid his eyes on her, he knew he'd give up his ticket to heaven just to make her happy. And if she wasn't in Heaven with him, he'd banish himself to hell.
He'd joyfully die if it meant she'd live. Ken'Ichi is your average quiet Japanese boy from an average Japanese household, with an average high school life, with high unattainable goals for his life and his childhood crush...if she wishes?
What happens when his heart is too much for his body?

"When life gives you lemons, you make-"She blurted out.
His dry, humourless chuckle emits from his hollow chest. "Funny thing is lemons are a crossbreed between a bitter orange and a citron, Life never gave lemons" Ever the smarty pants.
"NO! But Life allowed it, it made it edible. So you better make me a damn lemonade" Her balled hands shook with much rage at her side. How could he not understand? Lemons were the bitter things they were, but you dilute them in water and plop some sugar cubes in.

Teruya Ken'Ichi has a huge problem, he fell too in love. And is now diagnosed with Hanahaki disease, a rare sickness that affects one in a million. With only a few more days before Christmas, Teruya Ken'Ichi must write a long letter to Santa, requesting a miracle.