Fridge / Fist of the North Star

• Toki is the first to know the secret of Souther's invulnerability to Hokuto Shinken. Said secret is a medical condition... And Toki is a medic by choice.
• According to Kenshiro, by using the Tenryu Kokyu Ho (Art of Dragon's Breathing), the infamous shirt-ripping technique, he unleashes the full potential of his body, so why Raoh, Toki, and even Jagi never use it? Thing is, Kenshiro is the youngest of the four, and hadn't mastered it yet until around the Last General of Nanto arc (when he stops shredding his shirt). Thus every time he used it he ruined his shirt by imperfect use... Or, alternatively, the others have mastered it to the point they can keep it up the entire time.
• When one thinks about it, one would wonder why the Hokuto Hyakuretsu Ken hits so many pressure points. Uighur taking it and having to explode twice shows why: some rare individuals like Uighur are so incredibly tough they can survive most Hokuto Shinken techniques, but Hokuto Hyakuretsu Ken hits enough pressure points it will kill them - eventually.
  • The above explains why in the manga it's Kenshiro's go-to attack against the larger opponents: they're so big Kenshiro has doubts a normal attack will put them down, so he goes for the potential overkill. And indeed, the two most iconic victims turn out to be extremely tough individuals: Uighur survives the initial attack, and Zeed actually came out unharmed from the physical strength of the Hyakuretsu Ken in spite of having been thrown a few meters away and claimed the attack was like a mosquito before the pressure point strikes kicked in.
• In the anime Shin turns out to have a pressure attack that operates similar to the Hyakuretsu Ken. As Nanto Seiken is the twin style to the infamously Crazy-Prepared Hokuto Shinken and an assassination style, it makes sense they have a few special techniques just in case they stumble on an opponent that is somehow immune to normal Nanto techniques - just like Balcom, who could harden his muscles to the point of shrugging off Shin's usual attacks.