Accel world, vol. 6 (light novel): shrine maiden of the sacred fire, paperback/reki kawahara

The silver wings responsible for the rise of Nega Nebulus, the legion led by Kuroyukihime, are weakeningDuring the battle with the mysterious Acceleration Research Society, Haruyuki sustained corrosion damage from the revived Chrome Disaster, and he has still been unable to escape its effects.

The Seven Kings of Pure Color take this very seriously, and soon they hand down their judgement: purification.

Now Haruyuki is faced with a choice--undergo the grueling purification process, or have a bounty on his head and risk being cast out of the Accelerated World altogether.