- Before the timeskip, Meguru and Takashi as kids get in a fight with three older kids and find out that some basic knowledge of karate just isn't enough against untrained opponents that are more numerous, more experienced in fights, and larger to boot.
- After the timeskip Takashi discovers that being a good karate-based teen amateur MMA fighter just isn't enough against an experienced bodyguard with a past as a professional boxer, especially if one can't defend against hooks at the torso (and Takashi trainining specifically for those gets him through a number of fights), and later the flashback of Takashi's time in an orphanage shows what happened when a teen with some basic knowledge of karate and no body conditioning gets in a fight against a larger opponent.
- Takashi's father used to get in many fights as a teen, and later left his family to have a career as a karateka in Tokyo expecting a cakewalk. His arrogance crumbled when he discovered that Tokyo had karatekas from all around Japan with many stronger than him, and his attitude eventually pushed him to join the Yakuza.
- During the timeskip, Takashi trained hard so to be able to kill the man responsible for his father's death, counting on his yakuza uncle, who wants him as his heir, to be able to confront him as soon as he gets out of jail. Takashi finds out that his father's killer has been murdered in jail, and it's implied the order came from his uncle, who didn't want his chosen heir to get in jail for murder.
- Later Takashi beats up a thug that had got on his uncle's "punishment list" because his attitude risked to get them in trouble with the law, and lets the friend hired to capture him take him to his uncle. He later finds out that the yakuza wanted the thug dead for resisting the initial attempt at punishing him (why Takashi went to take him down: his friend had been beaten up and captured and was risking to get killed) and had Takashi's friend take the fall so he wouldn't risk jail for the No-Holds-Barred Beatdown he gave him, with the friend gladly accepting because while he had little choice but becoming a yakuza Takashi had a brighter future ahead.
- After being convinced to enter a MMA match, Maki neglects to train in grappling beyond some basic defensive technique, expecting to carry the day anyway thanks to the reach given her by her height and her powerful kicks. Her opponent, Kaoru, takes quite some damage but eventually forces her to submit in grappling.
- Proper dieting to get in a weight class is quite hard. Urasawa's defeat in a match is blamed partly on him failing to lose weight properly, and Meguru gets in the Kanto Tournament because one of the contestants in his weight class couldn't pass the weigh-in due getting too muscular.
- Four untrained and arrogant thugs with knives are no match for a good MMA fighter that isn't pulling any punch, especially if he's smart enough to attack first with no warning. To the thugs' credit, one of them went immediately for the drawer they were keeping a gun in, but Takashi saw him and broke his hand with a kick first-because he knew perfectly he would have been no match for a gun.
- Getting in an openweight tournament can have someone forced to fight an opponent two or three times their size-and that can close the gap even against a master of technique.
- Proper physical conditioning is extremely important. Momoko, being a genius at Judo and Ju-Jitsu, would often neglect it, and, as Yudai points out before it happens again, she often lost tournaments because she got too tired.
- On the same, proper physical conditioning takes time. Momoko's defeat for tiredness at the openweight tournament happens after she starts training properly, but only a few weeks of training didn't give her enough stamina to properly fight five matches in one day (two in a bantamweight tournament, and three in the openweight. The semi-finals opponent being a 1.80 meters giantess who was informed of her poor conditioning and took advantage of it didn't help arriving fresh at the finals).
- While having a favored technique or combo is normal, someone getting fixated with a specific one ends up being prevedible and easily countered by a more rounded opponent, no matter how good they are at said technique. It gets to the point that, while watching the match between Meguru and known "ankles maniac" Masuoka, Kagaya can anticipate that Masuoka will launch his final attack by jumping at Meguru's ankle-and that Meguru will knock him out with a knee strike.
Reality Ensues / All Rounder Meguru