Tonikawa: Fly Us To The Moon

Everyone that watched this anime for the first ten minutes would know how the story begins.
A young boy, determined to leave his name in the history books, getting saved one snowy evening by a young girl.
However, those people won't know how a girl, despite getting hit by a literal truck, survived.
For those who truly know how this story goes, they'll know that the girl is immortal, unable to die until the end of time itself. She saved the boy, by taking the blow and feeding him a bit of her blood.
What if that blood did just a bit more than she planned?

This is a continuation of the tale of the bamboo cutter...
Where Kaguya-Hime was taken back as she was returning to the moon...
And got happily married...

This is the story of a married couple...

The story of two immortals.