Kensuke Chisaka

After trying to rescue a man on the subway tracks, two teens wake up in a room dominated by a mysterious black sphere that sends them to hunt down and kill aliens hiding on Earth.

Summoned by the black sphere, Kei and Masaru fight against extraterrestrials until Masaru grows tired of fighting and refuses to continue.

Natsuki takes care of her young autistic brother. She then meets her old childhood friend and falls in love, unfortunately he suffers from a serious illness.