Natsu no Arashi!

Hajime Yasaka meets a strange girl named Sayoko Arashiyama (AKA Arashi), who turns out to be a ghost from World War II. They have the ability to connect, and together, they travel back in time to save Arashi's friends and family from American air raids. Along their adventures, they meet Jun Kamigamo and Kaja, who can also connect and time travel. Two other ghosts from the World War II era, Yayoi and Kanako, drain Arashi's existence so they can continue to exist. Hajime fights to save Arashi, but ends up connecting with Yayoi as well and travels back in time with her as well. (Source: ANN)