Abe beats reigning world champion to take last spot in Japan's Olympic judo squad at men's -66kg in bout that stopped a nation.
At the famed Kodokan in Tokyo, the 23-year-old two-time -66kg world champion eventually won 20 minutes into golden score with an ouchi gari throw (inner leg sweep).
The match was primetime viewing in the homeland of judo with many seeing it as tantamount to an Olympic gold medal decider, such is Japan's superiority in this weight class.
Emotions poured from both judoka following the first - and perhaps last - single-match Olympic qualifier in Japanese judo history.
Abe joins younger sister and two-time reigning women's -52kg world champion Uta - who was in the stands screaming with joy at the finish - on the Japan team for Tokyo 2020.
"The match was really long but I remember every scene," Abe said afterwards. "A lot of emotions flowed through me over the last several days but today, I just had to go out there and do it.
"It was do or die. I had the will and never doubted myself for a moment throughout the match.
"Now I can officially say I'm aiming for a gold medal with my sister at the Olympics. As her bigger brother, I can't afford to lose." - Hifumi Abe
Maruyama, whose shirt was covered with Abe's blood, was gracious in defeat.
He said, "The result is everything. It flew by. The verdict is in but I did everything I could.
"Abe made me tougher mentally. There's no question he made me a better judoka.
"My judo career isn't over yet. I have to keep my chin up and come back stronger, mentally and physically."
Such was the tension inside the Kodokan, which was sealed off to the public amid intense security, that Abe and Maruyama could be heard breathing from the stands.
Several of the sport's past Olympic champions - including legend and Japanese Olympic Committee president Yamashita Yasuhiro - were on hand to witness what was being billed as the match of the century.
They were not disappointed and neither were close to 400,000 people watching the live stream around the world.
Abe, four years his opponent's junior, was the more aggressive of the two with Maruyama handed the first shido penalty with 1:20 remaining.
Abe missed with an attempted shoulder throw inside the last 30 seconds but it remained scoreless with the match going into extra time for the seventh time in eight career meetings between the two.
Maruyama - who had held a 4-3 head-to-head advantage going into the bout - just missed with a side shoulder throw of his own but both struggled to come up with a decisive technique and were instructed again nearly two minutes into golden score.
Abe's attempted leg sweep at 3:16 was repelled as the intense stalemate continued.
After 8:35, Abe had to receive medical attention to a cut on his left middle finger, giving both judoka a welcome break after nearly 12 minutes of jousting.
It turns out they were only halfway through.
Shortly after resumption, Abe came closest to breaking the deadlock as he hooked Maruyama's leg but his rival just managed to stay loose.
With almost a dozen minutes gone in sudden death, Abe received his second shido meaning one more penalty for either would spell the end of the contest.
There was another delay at 18:19 as Abe suffered a nosebleed, needing a piece of cotton wool to stop it.
But with almost exactly 20 minutes on the clock, it was Abe who came up with the final move of match, getting inside position to leave Maruyama crestfallen.
Abe said being able to keep his cool throughout the marathon was key to the victory.
"Even though the match wore on, I knew what I was doing the whole time - good and bad. I stuck to the judo I know from start to finish and that's what led to the throw at the end."
Japan men's head coach Inoue Kosei said it was a shame he could not pick both for the Games next summer.
"I would have liked to select them both to compete at the Olympics but, unfortunately, I can't. They poured their heart and soul into this and sacrificed a tremendous amount to get here.
"But I know Abe will fight for Maruyama and Maruyama will use this experience to fight back."