Y/n that used to be a commander as he confess to the shipgirls but got rejected since then he went missing. He was in a dimension fill with endless void with a girl that look like him as they become friend, later on he have almost lose his eyesight as it have become very bad because of how long he been in the void so the girl have to guide him. One day a accident happened making him lost his memories and as she and him train to have to be aware of your surrounding but still can't see. The portal one day open and pull them in, Y/n and the girl fuse so he can see what going on while the girl is in a ghost/spirit form where other can't see her unless Y/n or she want to be seen.