Tomoa Narasaki thrilled the home crowd in Hachioji as he added the combined title to his bouldering crown at the IFSC Climbing World Championships.
The Japanese took a solid advantage into the lead section after finishing second in speed and winning the bouldering element.
And with his nearest challengers disappointing in the final discipline, Narasaki was assured of victory - and a place at Tokyo 2020 - before he took to the wall for the last time.
The 23-year-old from Utsunomiya was determined to put on a show for the locals and fairly flew up to hold 30 to take second place in the lead behind defending champion Jakob Schubert who was the only man to reach the top.
That gave him a multiplied total of 4.0, well clear of Schubert in second on 35.0 with Kazakh speed specialist Rishat Khaibullin taking the bronze with 40.0.
Tomoa takes charge
The contest was billed as a duel between Narasaki and reigning champ Schubert who had already taken bouldering silver and lead bronze at these World Championships.
Much would depend on their respective performances in the opening speed section, their weakest discipline.
But Narasaki has clearly worked hard in speed and beat younger brother Meichi in his first contest with Schubert losing to France's Mickael Mawem meaning he could only finish fifth at best.
Narasaki then clocked an impressive 6.159s to beat Mawem before slipping in his final against Rishat Khaibullin who won in 5.915s.
Kai Harada defeated Mawem to take third with Schubert down in seventh place.
Japanese climbers dominated the bouldering with Tomoa Narasaki leading the way with three tops and three zones from the four problems.
Meichi Narasaki was second from Kokoro Fujii with Mawem fourth and Schubert fifth having only managed three zones.
Germany's lead silver medallist Alexander Megos, eighth after the speed, was forced to withdraw after injuring a finger on the first boulder problem but - with four Japanese in the final - he had already booked his place at Tokyo 2020.
Megos still beat Khaibullin in the bouldering, but the Kazakh was in second overall on 8.0 behind runaway leader Narasaki on 2.0.
With Khaibullin unlikely to pose a threat in the lead, the only danger to Narasaki was brother Meichi on 10.0 although fourth or better would guarantee Tomoa gold.
Schubert put his previous disappointments behind him to top the lead route and move into medal contention.
Meichi Narasaki fell foul of the tricky mid-section, coming off at hold 21, to go fourth in the lead and he was surprisingly overtaken by Khaibullin.
Khaibullin led on 32.0 points from Schubert on 35.0 with Tomoa Narasaki guaranteed the gold.
The home favourite used some of that speed work to move quickly up the climb and came off at hold 30, enough for second place which saw Schubert move above Khaibullin into silver.
Qualification for Tokyo 2020
With just two spots per country up for grabs in sport climbing's Olympic debut at Tokyo 2020, the Japanese climbers - bar Tomoa Narasaki - face a nervous wait to see who will get the nod.
The four non-Japanese finalists will all return in less than a year's time along with Italy's Ludovico Fossali and Canada's Sean McColl, the three-time world combined champion, who booked their berths with top-10 placings in Sunday's qualification round.
But there is no doubt about the man they all have to beat in Tokyo with Narasaki senior a warm favourite to win the first Olympic gold in sport climbing.