On the Day Before Christmas

Satoru was born with a strange constitution.

Every year, on the 24th of December, tears would start streaming down his face, and his heart would be filled with a mix of regret and sorrow so intense, it would make his younger self bawl himself to exhaustion - and his older self brood all on his lonesome during the festive day.

No doctors can find out the reason for these tears. No medicine can cure him of this bizarre condition. Every year, when everyone else is out and about to have fun, he is forced to stay home with his eyes swollen and his mood sinking to the bottom.

Until one day, on the first Christmas Eve after his 17th birthday, he decided to leave his house out of desperation - where he met a stranger who shared the same constitution as him.