The Earth receives an influx of X refugees, who were deported from their home planet due to a dispute. Countries on Earth agonize over how to deal with the influx of these interplanetary immigrants. The U.S. government announced that they would accept X refugees, and the Japanese government announced that they would also accept X refugees.

The X refugees transform their appearance into human beings and live among ordinary humans. Residents in the host countries are unable to distinguish X refugees by appearance, and they have no idea if any of them live among them. People become anxious, confused, and afraid of the X refugees, and they try to find the refugees who may live among them.

Sasa Kentaro is a weekly magazine journalist. For a story, he hides his identity as a journalist and approaches Kashiwagi Ryoko, who is suspected of being an X refugee. He gets close to her and begins to have feelings for her, but he's not certain if she is human.

(Source: AsianWiki)

Adapted from the novel "Rinjin X" (隣人X) by Pallus Ayako (パリュス　あや子).