Inoue, whose amateur record suggested little of his success in the paid ranks, halted Narvez, 39, in just two rounds to record the seventh stoppage of his career – with only compatriot Ryoichi Taguchi able to take him the distance so far.
The victory means Inoue becomes a two-weight world champion at the tender age of 21 on the back of the talented Japanese puncher already banking the WBC title at light-flyweight in his fifth fight last April.
Opponent Narvaez suffered just a second loss in 47 contests as former pound for pound star Nonito Donaire was the only previous competitor to hold a victory over the seasoned southpaw.
Also on the bill, Japan-based Venezuelan Jorge Linares finally captured the maiden championship of his rollercoaster career as ‘El Nino de Oro’ stopped Javier Prieto in four rounds to claim the WBC lightweight title.
Linares, 29, previously suffered crushing back-to-back losses to Antonio DeMarco and Sergio Thompson in 2011 and 2012 whilst on the cusp of claiming WBC gold, but can now celebrate his new found status.
Pedro Guevara will also be added to the WBC champions roster following the Mexican’s seventh round knockout over Akira Yaegashi as the 25 year-old picked up the 108lb WBC belt vacate by headliner Inoue.
Ryo Matsumoto, Ryota Murata and Takuma Inoue all remained undefeated on the undercard at the Metropolitan Gym in Tokyo.