From iskultrip Scans:

Japan wields the power of a new form of influenza so lethal that only one person out of a million can survive an infection. Kazuma, a man able to withstand the infection of the unknown virus, "Cherubim [kerubimu]," has obtained the power to save his twin sister from facing the influenza! While Kazuma saves other people's suffering by using his new power, he will also encounter many surprising and painful things… A serious and comedic story of new abilities begins!!