After a momentous 2019, find out how the three-time swimming world champion overcame his small stature, who his hero is, and why the medley may be Japan's favourite event at the Olympics.
With three individual long course world titles, two Asian Games gold medals, a Pan Pacific victory, and a world record in this Olympic cycle alone, Seto Daiya is no longer Japan’s most underrated swimmer.
For years, the softly-spoken butterfly and individual medley specialist has played second fiddle to his better-known compatriots.
Two years later at the 2018 Asian Games, Seto’s two gold medals were overshadowed by teammate Ikee Rikako's amazing eight-medal haul.
Unfortunately, a period of depression and lack of motivation led Hagino to take a break from the water after Rio, while Ikee is this weekend set to compete for the first time since her diagnosis with leukaemia in February 2019.
Their absence suddenly turned the spotlight onto Seto at the 2019 FINA World Championships in Gwangju, Korea.
With less than a year to go before Tokyo 2020 (before the pandemic-enforced delay), Japan needed someone to deliver, and Seto - who many seemed to have forgotten had won the 400 IM world title in 2013 and 2015 - stepped up in style.
Silver in the 200m butterfly, where he beat London 2012 Olympic champion Chad le Clos and was only bettered by Kristof Milak’s new world record, was followed by victory in the 200m and 400m IM. Japanese swimming had its new hero.
The Saitama native took up swimming at the age of 5. He also gave volleyball, skateboarding, and snowboarding a try, but it was clear that his strong physique was best suited to the pool.
Seto broke the Japanese 400m IM schools record, and secured several national titles, and his inspiration was unsurprisingly the most successful Olympian of all time.
“His concentration going into each race was on another level. You need that kind of focus to be able to compete in numerous events.
“When I was younger it was just about swimming as fast as I could. I never saw myself as a great talent or anything. I just wanted to work hard so I could one day become an Olympic champion.”
But unlike Phelps, Seto was not born with the kind of long limbs that propelled the American to 23 Olympic gold medals.
At 1.74m (5-foot-9) and 73kg, he is significantly smaller than most of his international rivals. Hagino cuts a similar frame to his compatriot, but when compared to medley champions like Phelps (1.93m, 88kg) and Ryan Lochte (1.88m, 88kg), it is clear that Seto is at a distinct disadvantage.
But what he lacks in size, he makes up for in heart, and his relentless intensity in training is well-documented.
That he should have achieved so many world titles so early in his career without the natural athleticism of his rivals, is another achievement that perhaps doesn’t get the praise it deserves.
Seto’s mentality is the bedrock of his success, and has helped him get through some tough times.
At Japan’s London 2012 Olympic trials, the then-17-year-old agonisingly finished third in both the 200m and 400m IM, meaning he missed out in both events by one position.
But that disappointment was quickly turned into motivation, and in 2012 he was crowned the short course 400m IM world champion, before adding the long course title to his resume in 2013.
It’s telling of Seto’s mindset and determination to win Olympic gold that, even after winning three 400m IM world titles, he still sees vast areas where he can improve.
“In order for me to swim in the 4:05-s, I need to work on my freestyle,” the father, who has a 400m IM personal best of 4:06:09, told Swimming World Magazine.
“At the Olympics, I’d like to make sure I swim in the 4:05-s so I’ll have a legitimate chance to win. I’m determined to overcome gruelling training, so I’ll be ready for next year.”
While many athletes would have taken some time out after ensuring their country’s qualification for the Olympic Games, Seto signed up to compete in the World Cup straight after the 2019 world championships.
“I put a huge amount of effort into the World Championships and it’s a great competition to win, but honestly speaking I see it more as a stepping stone to something bigger,” Seto told Tokyo Weekender.
“The ultimate goal is to get a gold medal at the Olympics. That’s something I’ve been dreaming about since I was a child.”
The men’s individual medley at the Tokyo Olympics in 2021 is sure to be one of the hottest tickets in town.
The delay to the Games caused by COVID-19 has given a rejuvenated Hagino the opportunity to defend his Olympic title in home water, while 200m and 400m IM 2017 world champion Chase Kalisz will be intent on redemption after surrendering his titles in a disappointing 2019 world champs.
All three men are 26, meaning that whatever the result is in 2021, this rivalry could potentially be around for at least one more Olympic cycle.
Add to the mix Australia’s two-time Olympic medallist Mitch Larkin, who is considering switching to the 200m IM, and potentially London 2012 400m IM Olympic champion Lochte, who has made a return to the sport, and the medals are near impossible to predict.
Speaking to Olympic Channel after winning the 400m IM world title in 2019 about the pressure and expectation that must now surely be on him for Tokyo 2020, Seto seemed relaxed.
“I don’t feel the big pressure,” he said in English with a smile. “Just swim and give my best.”
With such a steady head on his shoulders, and a seemingly unwavering determination to win Olympic gold, it is unlikely Seto’s name will be left out of the conversation again.