Last Round Arthurs, Vol. 5 (Light Novel): Once King & Future King, Paperback

What's there to greet Luna and Rintarou upon their return from their journey is the doomsday clock. It's said global annihilation will be triggered when King Arthur resurrects from the age of legends-and the countdown is getting ever closer to this fated moment. The other candidates for the throne balk at the task ahead of them...and Luna steps forward to participate in a final battle that transcends time.