The taller and stronger Japanese southpaw was in command of the fight most of the way, pinning Sultan against the ropes on that fateful seventh round where he peppered the Filipino challenger with a fusillade of telling shots to the head and body.
Hidaka kept on pounding on the hapless Sultan until he let loose a wicked left that promoted Australian referee Malcolm Bulner to wave off the fight at the 1:07 mark of the seventh frame to prevent fallen SGG Stable warrior from further damage.
The WBC ranked No.10 147-pounder Hidaka bettered his win-loss record to 22-4 now packed with 16KOs, while Sultan suffered his fifth defeat in 18 professional fights that include two draws and five wins via stoppage.
It was Hidaka's first successful defense of the OPBF crown he seized after dethroning the Cebu-bred Rev "The Gentle Giant" Santillan of RWS Stable last March.
Sultan, on the other hand, faltered in his OPBF title shot for the second time, with the first via a controversial split decision loss to Hiroshi Watanabe two years ago also in Japan.
Japanese impresario Joe Koizumi, the matchmaker of the card promoted by Shin Nihon Kimura Promotions, said that Hidaka will be obliged to battle Santillan within this year due to the option agreement.