GO! GO! Ghost 2015 (GO!GO!ゴースト2015 GO! GO! Gōsuto Nisen-Jūgo) is the fourteenth episode of Kamen Rider Zi-O. It is the second part of the Kamen Rider Ghost and Kamen Rider Decade dual tribute arc, and features the return of Kamen Rider Specter portrayed by Ryosuke Yamamoto. It also features the debut of Zi-O DecadeArmor, Zi-O DecadeArmor Build Form, Zi-O DecadeArmor Ghost Form, Decade Ghost, the Genm and Cross-Z Modes of Geiz's Time Mazine, the Ex-Aid and Build Modes of Zi-O's Time Mazine, and the Ride HeiSaber.
This episode is accompanied by the fourteenth episode of Kamen Rider Zi-O: Supplementary Plan web series, Pink Devil.
Sougo has become a ghost! His spirit is invisible to both Tsukuyomi and Geiz! In order to return Sougo back to normal, Geiz travels back to the year 2015! Geiz encounters and starts to fight Another Ghost in 2015, but just then, Kamen Rider Decade appears!