From MangaHelpers:
Chigira Yuusuke is a young man who seems to have lost his memory. He spends his peaceful days working part-time and wearing a "Pale Rider" mask outside of work. One day, his life changes due to a fateful encounter with a young woman named Amemiya Miyako, who he meets shortly before an unexpected attack turns Tokyo into a sea of flames. What is the purpose of this attack, and could Amemiya hold the keys to unlock Chigira's past?