Do you have any good manga oneshot recommmendations where the girl or boy main character already died or appeared in ghost form? Or any bittersweet ending? Something like they did not end up with each other? A story like will make you cry or something to be sad about?

Dare mo Shiranai 29-nichi - romance between guy and ghost
Sekai de Ichiban Utsukushii Namae - historical, girl and ghost
49 - not a one-shot, but a one volume manga about a girl and a ghost

Others that are just sort of sad/bittersweet:

Kon no Ki Konoha
Fuyu no Hana
Akuma ni Itsukushimi no Te wo
Ao to Umibe no Nostalgia
Tenkousei, Ridatsu suru

Thank you very much!!! Any other else minna-san?