Eyeshield 21/Heartwarming

For one, after Sena finally revealed his identity to Mamori, she instinctively told him to win against the Bando Spiders. There's kind of a lot involving Sena and Mamori, actually.
During the match against Shinryuji Nagas, Sena's leg was in verge of destruction to keep up with Agon. Mamori sees this, and worried about Sena's legs. Then, she said "Sena, please win!" knowing that Sena won't go back down, unlike some coward kid she used to protect earlier.
For another, when Leonard Apollo, coach of the NASA Aliens, finally realized that he had been treating Panther the exact same way his coach in the NFL treated him, saw that Panther had always respected him and been a fan of his despite the abuse he piled on him, and gave Panther the spot on the team he always deserved.
- Or when all of his team knelt down just so that Panther may enter the game.
Then there's Daisuke Atsumi of the Yuuhi Guts during the last moments of the game against Deimon. "I'm Daisuke Atsumi... and this is my last play!" The fact that the Guts were going to lose no matter what, and Atsumi's last play was destroyed by Eyeshield 21 himself kind of compounds it.
Sakuraba gets a lot of these. When his fangirls come back to him, for starters.
- When he heard Takami's praise and hopes for him from behind the wall.
Monta receiving a compliment from his hero, baseball player Masano Honjou after catching a ball aimed at the back of his head.
When enormous Hakushyuu Dinosaurs lineman Rikiya Gaou threatens to rampage through the stands breaking bones to avenge an insult from the audience, Mamori immediately pulls Suzuna behind her to protect her, but then Hiruma leaps in front of them, brandishing multiple tazers, and immediately afterward the Ha-Ha Brothers all jump up wielding their delinquent bats to follow Hiruma's example.
The scene at the end of the Bando Spiders game when an exhausted Sena staggers in and collapses into Suzuna's arms. Her initial shock and embarrasment gives way to acceptance and she asks him if he's grown taller.
Hiruma forgetting about facts and numbers for one second and actually straight-up believing in his team.
Yukimitsu's first touchdown was combination of this and Crowning Moment of Awesome.
Musashi watching the Devil Bats losing on the television in his father's hospital room, unwilling to return to the team waiting for him until his father punches him and the workers at his company all show up to tell him that they'll carry his share of the load.
When Monta gets discouraged about having to face his idol's son (and because Sena accidentally wrecked his prized catching glove), Sena runs around collecting the gloves of the other receivers and cornerbacks he faced to rally his spirit and confidence.
When Yukimitsu isn't picked to start for the Devil Bats and breaks down in tears after everyone leaves. Sena and Monta, knowing it will just make it worse if they go and comfort him, loudly declare off to the side that they will stay in the tournament as long as they can so everyone (meaning Yukimitsu) can play.
Before the Christmas Bowl, the Teikoku Alexanders with their huge roster, seemingly invincible record, and solid tradition of winning even have a huge snow sculpture of their mascot at the entrance of the Tokyo Stadium. Habashira Rui (of all people) sees this and gets pissed off that one team should have so many advantages while the other team has so few and orders his team/gang to the Tokyo Stadium to build an equally huge snow sculpture of the Devil Bat. Awwwww.
When Hiruma realizes it's impossible for them to win the Christmas Bowl he takes a moment, puts on his scary face and tells his team a whopping lie about their great chances. They all know he's lying. They believe him anyway.
Hiruma gets one when Zokugaku loses their chance at the Christmas Bowl and Habashira Rui comes to him for advice. "YOU AND ME, WHAT'S SO DIFFERENT!?" Hiruma gives no answer, but the panels to his left clearly show what he thinks.
Hiruma after breaking his arm facing down Gaou and lying on a stretcher kicking a crying Kurita in the butt to get him going.
Agon, in match against Americans, finally removing his wig, in respect of his brother and Habashira. Yes, this Agon.
‎Musashi's triumphant return to the Devil Bats: "You're thirteen thousand, two hundred and ninety-seven hours, forty-nine minutes late."
When the Devil Bats have tryouts, the candidates are to climb Tokyo Tower carrying a bag of ice in extreme heat (along with other obstacles). If they make it to the top with at least one ice cube left, they make the cut! As you can imagine, mostly everyone gives up. But not Yukimitsu even though he's clearly no athlete. He finally makes it to the top, but all of his ice has melted. Hiruma then sneakily grabs an ice cube and plops it into the bucket, informing everyone that Yukimitsu has qualified for the team!
On the Death March, Sena won't leave anyone behind. Also a Moment of Awesome for Sena.
The Backstory of how Hiruma, Kurita and Musashi met. Can also count as a Crowning Moment of Awesome since it showed Hiruma as the Jerk with a Heart of Gold he is. Not an easy feat.
The Rousing Speech Hiruma gives to Musashi right before the final play of the Christmas Bowl. Sorry, but it must be quoted; "When you left the team that day, do you know how much Kurita hit things ind despair? And when he ran out of things to hit, do you know how much he screamed? Kurita... Do you know how much Kurita was...!" (background panel flashes to Hiruma himself kicking the bench out of despair) "KEKEKE! YOU'D BETTER SETTLE THAT DEBT RIGHT HERE, ONCE AND FOR ALL! SCORING THAT IMPOSSIBLE KICK IS YOUR JOB, FUCKING OLD MAN!"
Marco, post-defeat, realising that in trying to win over his crush, Maria, he's driven her away completely...and in admitting it, winning her over again. Ahhhh.
Sena's father cheering Sena on and telling him to continue on, even before knowing that his son was Eyeshield 21.