World champion wins signature 400 IM after serving suspension for ethics violation as Japan Open gets under way
The world champion didn't need a whole lot of time to shake off the rust, as he led from start to finish, touching the wall in 4 minutes, 12.57 seconds at Tokyo Aquatics Centre, the swimming venue for the Tokyo 2020 Olympic Games.
It was Seto's first competition in 144 days. He had been banned by the Japan Swimming Federation for an ethics code violation.
Rather than reflect on the win, the first thing Seto did in his first public appearance since September was to profusely apologise for the actions that had cost him his captaincy on the Japan national team as well as several endorsement deals.
"First of all, I would like to apologise for my careless actions last year", Seto said after the race. "I disappointed a lot of people starting with my family, friends, sponsors and everyone who had supported me.
"During my suspension, I spoke to a lot of people and it made me realise how good I had it. I wasn't aware of how fortunate I had been and I blew it, acted irresponsibly.
"I'm just grateful to be swimming again. I hope I can repay everyone through my performances."
"Winning an Olympic gold medal is a childhood dream of mine and that has not changed. If anything I want it more than ever - but for all those who helped me through a difficult time". - Seto Daiya
Seto - the only Japanese swimmer to have already qualified for Tokyo 2020, by winning at the 2019 world championships - was far off his personal best of 4:06.09.
But he never looked to be in danger of losing the final after qualifying second overall from the heats in 4:14.98 despite ballooning to 81 kilograms during his suspension.
Seto said he is now down to around 76kg after working out the past month at the National Training Center.
All eyes were on the renewed rivalry with his good friend and Rio 2016 gold medallist Hagino Kosuke, but it wasn't even close on this occasion.
Hagino, looking tired after an intense winter of training and competing, finished a distant seventh (4:16.38).
Seto will have an opportunity to further whip himself back in shape on Saturday, when he is entered for the 200 IM and 200 butterfly.
"It was good to be swimming with Kosuke again. He brings out a better version of me", the 26-year-old said. "I'm not happy with a 4:12 though.
"I wanted to crack 4:10 but wore out in the end. It was great to be able to swim in the actual Olympic venue. It's a fantastic pool and I'm glad I had the chance to swim here."
"A lot of emotions in me today but I'm trying not to get ahead of myself. I'm only thinking about the next race." - Seto Daiya
Nineteen-year-old Boy Wonder Sato Shoma continued his rise to stardom, holding off former world record-holder Watanabe Ippei to win the 100 breaststroke in 59.67 seconds.
Watanabe came home 0.08 behind in his first start of the Games year after skipping the Kosuke Kitajima Cup two weeks ago - when Sato joined the select 2:06 club in the 200 breast.
Sato's time of 2:06.78 ranks as the fourth fastest in the history of the sport and just 0.11 off Watanabe's Japan record.
Thursday's duel sets up a mouth-watering showdown between the two on Sunday in the 200m, when Watanabe believes a new national record will be set.
"I think Sunday’s 200 will be a huge race looking ahead to April", Watanabe said, referring to the Olympic trials.
"I think Sato will want to break the Japan record and as the record holder, I’ll give that race everything I’ve got".