The Winter Sea Where You Are Gone

Winter sea surrounds the moment of the high school graduation.
Sena and Shu, two classmates who exchanged words just once, and who followed different paths for about two years, reunite in front of the very same sea.
They spent a year together as if they wanted to fill in the gaps inside each other's hearts.
One day, without having opportunity to express their feelings and maintaining an ambiguous relationship, the accident happened.
Shu wakes up at the hospital and runs to find Sena, the latter calls him by his last name, "Kutsuna,"... Why now after all this time?
If you forget our year together, does it mean it is the end of our love as well...?