The 22-year-old is both a former and current Blade, a coach at the United academy and a fan of the club from birth. A Blades goalkeeper since the age of nine, he graduated through every age group and won 30 England youth caps before making it, with a professional deal.
But that was only the start. Injury to Mark Howard left Willis and George Long fighting for the No.1 spot - in one game, the pair’s combined age was less than the opposition’s goalkeeper - but the bench was as far as he got.
The end came in 2016, almost lost amongst the noise as Nigel Adkins’ disastrous season in charge at Bramall Lane began to unravel. Adkins, who had informed Willis that his time at United was over the previous month, was out himself after leading the club to a disastrous 12th-placed finish in League One and suffering the ignominy of a end-of-season ‘lap of honour’. For the barely 100-or-so fans that could even face staying a moment longer, it was more of a blood-letting exercise.
After five, miserable seasons in League One, their club was at rock bottom. Then, out of the smouldering remains of Adkins’ reign, emerged Chris Wilder and what has followed - 100 points, the League One title, derby wins away at Sheffield Wednesday and Leeds, another promotion tilt - will go down in history.
Willis’ smiles ruefully at the thought of being a part of it.
“Chris has done an unbelievable job,” he says - like many, struggling to find the adjective to do it justice.
“He came in and surrounded himself with the right people, people who have this club at their heart - like himself, Billy Sharp and a few others.
“Obviously, I do too. So maybe things could have been different. Who knows?
“But I can’t have regrets. It’s football; a ruthless environment, and a business. So looking at regrets is pointless, because any footballer’s journey will have so many ups and downs. Hopefully, there’s more of one than the other. But no regrets. None at all. It’s football.”
So while Wilder and some of Willis’ former teammates and coaching staff were soaking Sheffield in Peroni, the goalkeeper was enjoying a promotion of his own, moving from Gainsborough Trinity to Boston United.
The day after we meet, Willis’ Boston were beaten 3-1 by a Harrogate Town side containing former Blades teammate Terry Kennedy - a reminder of the precarious industry to which they both belong.
No snobbery here, though. Willis was offered a deal with League One side Oldham - as second or third choice, he remembers pointedly - on decent money. Most youngsters in his position, eager to keep the comforts and other trappings that having ‘professional footballer’ in their Instagram bio bring, would have snatched at it.
“A lot of people tried to talk me into it, but it wasn’t right and it didn’t feel right. It wasn’t for me,” he says with a scratch of a beard that belies his age.
“They offered me a similar position that I had at United, as cover, on very little money. It was alright, don’t get me wrong - it’s brilliant being a footballer, after all. You’re paid for doing something you love. But I needed to play.
“And I thank myself now for making that decision. I knew I had to build a CV and so I couldn’t be snobbish and turn down teams where I knew I’d play, especially as a goalkeeper.
“It was a tough decision, of course, but I made the right one there. I always say to people, ‘do what will challenge you and improve you, not what makes you feel comfortable’. That worked for me. You do what you’ve gotta do, sometimes.”
Now, in between turning out for Boston, Willis is an academy goalkeeping coach at United - a role he began, curiously, while still a first-team professional on the Bramall Lane books.
“Ah, I love it,” he beams, when the conversation turns to coaching. He means it, too.
“I don’t think it’s something you can play at; either jump straight in and get your hands dirty, or don’t bother. When the kids are running riot and ‘keepers are smashing balls at each other on a Thursday night... it is what it is, and you’ve got to be able to enjoy it, to manage it and be able to develop the kids, too.
“As players, of course, but as people, too. That’s a big thing that Nick Cox and Travis Binnion [former and current heads of United’s academy] started - we have a duty of care to every child that we have, whether they make it in the game or not.
“So everything has a meaning. Walk through the door and say hello to people, shake their hand. Little things like that. It’s a harsh industry. If we have 20 in an age group and one makes it, that’s brilliant. But the other 19 have got to survive.
“I think the academy’s track record backs that up. To make it to the top you have to be technically good, but also have the right mentality and grounding. That’s what we give them.
“For these kids, I’ve been through the journey they’re taking not so long ago, so I know what it’s about.
“There were times last year when I’d be taking an U23s session with Jake Eastwood, who’s two years below me. Simon Moore was with the U23s in a game at Birmingham and I was the goalkeeper coach. He’s 27!
“So from that point, it can sometimes be a bit bizarre. But it’s football and we get on with it. There’s a mutual respect between goalkeepers, too, which helps. Simon and Jamal Blackman are top lads, and I’ve known Jake for ages.
“That’s the goalkeepers union people talk about.”
It extends to coaches, too; Willis namechecks United coach Darren Ward as a defining influence on his career, alongside Bob Widdowson, Jamie Annerson - England women’s new youth goalkeeping coach - Cox and Binnion.
“I was absolutely gutted to leave United,” he remembers. “I wouldn’t say I was pushed out, but I was guided down that route. I’d never have wanted to leave and previous managers were much more understanding of my position, letting me go out on loan. But Adkins didn’t see it that way, and that was that.
“I accepted it and got on with it. I’d have liked to have gone out under a loan banner, but it wasn’t to be. So I was chucked out and had to get on with it.
“As a player, you have to accept how the game works. Coming out of United, you get a lot more respect when people see you’ve done three or four years as a pro at a club like that.
“A lot of people get a one-year deal and filter down the leagues, so to do it for three or four years gets you that bit of respect and for me, just touching six feet, that’s a big thing.
“A lot of people will look and say ‘nah, not for me, not big enough’ which was what Adkins said to me.
“So, you have to build a reputation the other way.”
Despite Willis’ age, football now is still markedly different from his days as a youngster in the England set-up, playing alongside names including Raheem Sterling, Nathan Redmond and Luke Shaw and winning the Victory Shield.
“Goalkeepers don’t just stop goals now... they help create them,” he laughs.
“It’s crazy. Some managers ask about a goalkeeper’s feet before his shot-stopping. Look at the likes of Jordan Pickford now, kicking it the length of the field and within two seconds, Everton have scored.
“Someone like Simon Tracey used to pick the ball up, run to the edge of the box and just smash it as hard and as high as he could. That’s the evolution of football, I guess, thanks to the likes of Pep Guardiola.
“There’s a lot said about goalkeepers being mad, but you have to be smart to get to the top. I think it’s a lot easier to run round in midfield like a headless chicken, I think.
“You’ve still got to be crackers, but it’s become a really intelligent position. They say eight out of ten touches a goalkeeper makes now are with the feet. Ederson at Manchester City is probably at 9.9/10! It’s crazy, but you’ve got to adapt.
“And, I guess, you’ve got to love getting kicked in the face, too.”
Fortunately for Willis, that’s an experience becoming rarer and rarer in the Conference North, a division with a number of full-time clubs that the youngster believes is growing in standard by the season.
Gone, too, is the snobbery of the past from clubs. England goalkeepers Pickford and Joe Hart both have Conference appearances on their CV. Tom Heaton left Manchester United, arguably the biggest club on the planet, to play games and later worked his way back up to represent his country. Others have done the same; it’s a well-worn path that Willis hopes to also tread.
“The league we’re playing in is getting massive now,” he says. “You only have to look at teams like Salford to see that. I know lads that have been offered deals at League Two clubs and turned them down because the money isn’t as good. The money’s there and so are the scouts, because it’s a big pond for them to fish in.
“So I have ambitions to get back up, 100 per cent, and everyone at United knows that. I’m here to coach but if the chance ever came to go full time, I’d snatch it. They’ve been great with that.
“If not, I’ll always have the coaching side to fall back on. By the time players are looking to retire at, say 35, I’ll have over 15 years of experience on them.
“I like to think I’ll always have a career at the level I am at now and if that’s how far I get, then so be it.
“There’s ups and downs. But I have no regrets. It’s football.”