This is a piano & vocals sheet music of Masaki Suda & Huwei Ishizaki cover version of the song written by Miyuki Nakashima, which is also the original song of the movie "Ito" Key : A♭(By the way, Miyuki Nakashima is in B♭, that is -2 key)
The piano part of the original song has been faithfully scored, but arranged for playing along, but you may hold and play only the main chord tones where it is difficult to play while singing.
The lyrics are also included at the end of the score.