Nagi's finally back in his own body, but so is Sensei. Months after the showdown on the Takarabune, Sensei (and the Death Rock's) whereabouts are unknown and Nagi is doing physical therapy to try and regain the strength he'd lost after three years in cold storage. Meanwhile, Nina, the child Naozumi and Doctor Radio have been looking after, has made a mysterious new friend who may not have Nina's best interests at heart… Has Nagi regained his fighting prowess, or will his murderous intent be absorbed by a brand-new version of an old foe?