Trying to find manga o/

Hello I'm trying to find a manga that I haven't seen since a certain website died. I thought it was called Kairi but I haven’t been able to find it so I must be wrong. It was about a girl who was going on some sort of summer vacation and ended up finding what she thought was a body but was actually an immortal soldier. He is trying to help the ghost of another soldier trapped in a radio find peace. They're doing some traveling on trains when they get found by people from the governemtn tracking down and permanently killing what remains of the immortal soldiers. It was probably some sort of shojo?

Thanks in advance for any help!