『何か一つ、誰かひとり欠けていたら』
イフを前提に繰り広げられる前日譚と後日談。

今も続く、少年と吸血鬼の物語。

"If there was even just one thing, or a single person who was left out..."
A story that is both prequel and sequel, unfolding along a series of what ifs.
The story of a boy and a vampire continues even to this day.