Subarashiki Kono Sekai The Animation

Synopsis

Finding that he is the only player taking part in this game, Neku is defenseless against Kariya and Uzuki until Beat steps in and becomes his partner. Beat explains that Hanekoma managed to piece together Rhyme's soul and bring her back as a Noise and that he became a Reaper in the hopes of becoming the new Composer and returning her to normal. As Neku and Beat search for the current Composer's whereabouts, they are confronted by the third Game Master, Mitsuki Konishi, who captures Rhyme as Beat's entry fee for becoming a Player. The next day, Konishi issues her sole mission, to find and defeat her within the remaining six days, before using an Emergency Call to order all the Reapers, who are powered up with "O-Pins", to erase Neku and Beat. Heading into O-East to find Konishi, the pair are forced to fight against 777, who gives them their Key Pin after they defeat him before Konishi erases him for going easy on them.

(Source: Wikipedia)