It was a old song probably the songs came out year was 2014/2015 the music video is about a boy who sit in a train station and waiting for a train.
Then a girl show up. When he saw that girl he had flashbacks in the flashback the boy and the girl was seem to be happy to be together. But then the girl said something (probably about a illness i didnt understand idk japanese) and flashback over he remembered her but she didnt because she lost her memory and they saw each other in the train station after years which is they broke up.
And singers song was unique too he made me cry when i first listen to it. I dont remember the songs name because it was japanese but i remember the song and the mv