For a badass shonen series on martial arts, a lot of heartwarming moments occur nearly once an episode.
When the series begins, the one thing that keeps Kenichi returning to the dojo for his hellish training is Miu. Miu is the one dojo resident who acts like a regular human being and treats Kenichi as such. During a period where Kenichi is trapped in his own quarters overnight at the dojo, Miu beckons him over to the rooftop in her jammies so they can have a picnic and look at the stars. Awww.
Kenichi: "Actually, there's a feeling inside me that I want to express in words, but... I want to keep those words until I'm able to protect you. For now, all I can say is that I have that feeling inside me... Do you think I'm a coward?"
Miu silently shakes her head
Miu: "Because... if that's so... until now... not by your words... but by your actions... you have already told me. That's why... I will also... [do the same] with one action...
Miu proceeds to kiss Kenichi on the cheek!
Or she would've if not for the Ryouzanpaku Masters' Moment Killer.
The whole of Chapter 406. "I will protect him even if I die," in-fucking-deed!
Chapter 448 is pretty much one giant Heartwarming Moment. Kenichi has just had Miu kidnapped, and is so down in the dumps about it that he starts literally beating himself up over his failure to protect her. Cue not only the Shinpaku Alliance rallying around him, but the Yomi members at school offering moral support as well. Chikage does it in the form of chocolate!
Chapter 465 is this wrapped up with awesome. Miu and Kenichi have little celebrations of her having been brought out of Junazard's brainwashing even as they take down the insanely powerful swordsman Kenichi's been fighting thus far.
Chapter 496: Takeda is preparing to sacrifice his healed left arm to a YOMI submission/counter specialist so he can deliver a devastating punch with his right. Ukita desperately tries to get the others to stop him, not wanting Takeda to throw away everything he's gained back, but the others don't move, not wanting to interrupt the one on one fight. Finally, Ukita rushes forward, shouting, "If no one stops them then I will!! Before being a martial artist, I AM HIS FRIEND!!" This inspires Kenichi to break the fight before the YOMI breaks Takeda's arm.
Chapter 519: All of the Shinpaku's efforts on Defusing The Tykebomb Chikage Kushinanda have finally payed off. At one point, Kenichi asks Chikage, should she decide to stay with YOMI, to remember the times when they were friends. She does, and the results are adorable.
Chapter 539: Mixes this with awesome. Shigure, alone, faces seven masters, just so Miu and Kenichi will be safe. It didn't work, but the intent was amazing.
When Tanimoto loses consciousness during his fight Chou Enshin he (predictably enough) see's his little dead sister telling him not to "sleep here." Then he sees Honoka, his Replacement Goldfish, asking him to play Othello. Cute, but far from unexpected. Then he sees Kenichi telling him that "it's dangerous if you sleep here!" Aw, he really does care!