This drama is steeped in sepulchral undertones and it's evident that the entire message has a chance of missing its mark. It's not a 'story' per se, rather the journey of the characters in particular.

There is no mincing of words – An introverted, intelligent high-schooler, Mitsuru, loses his person, the popular Yamada Koichi in an accident, which happened right beside him. But, the ‘dead’ Koichi gets up in spite of clearly fatal injuries that should have killed him.
Mitsuru now helps his ‘living corpse’ of a friend to get back on track, but he starts to slowly realize that his presence is the only thing that keeps Koichi corporeal.

As a viewer, it's painful to watch as it is evident that Mitsuru was in self denial. He keeps trying to come up with reasons for Koichi to stick around and Koichi, knowing him, attempts his very best to keep Mitsuru happy.
In a way, Mitsuru, a usually quiet individual, speaks up and tries to get Koichi to live out his last wishes.

Mitsuru is a particularly hard character to play without appearing emotionless, so kudos to the actor for not making him seem indifferent. Koichi was much easier, but his story was sad in a way.

I watched this in January, and right now, all I can remember is Mitsuru crying. Hence, why I used the word 'memorable' fir the title.
It's depressing from start till the end. Maybe that's the pain of losing someone.
It's good for a slow watch, but I'll not suggest it to anyone who has had a difficult time getting over the death of a loved one.