北斗の拳①・Fist of the North Star book1 ch1

北斗星 is the big dipper

(七つが並んで斗（ひしゃく）状をなすのでいう）北天の大熊座にある七つの星。斗柄に当たる第７星を揺光といい、一昼夜に十二方を指すため、古来これによって時を測った。北斗。北斗七星。七つの星。

and not actually the North Star 北極星・Polaris. The constellation as visible on Kenshiro's chest is rotated 180°, with Polaris on the bottom (at Ken's abs). The star visible popping out of Ken's shirt on the cover is β UMi, or Kochab コカブ, which served as the North Star from 1500BC-500AD.

北斗神拳 Hokuto ShinKen is Kenshiro's fighting style, comprised of various techniques.
・拳 does mean Fist; however, the 3rd entry in 広辞苑 may shed a little more light.

二人以上相対して、手の開閉または指の屈伸などによって勝負を争う遊戯。本拳・虫拳・狐拳など種々ある。近世、中国から伝来。冥途の飛脚「－の上手」。「－を打つ」

so, playfighting from China that is organized into different 拳, 本・虫・狐 &c. well, this is 神拳, Gods Fist as it were (gods plural). Considering the themes of the story thus far (accupressure, lone wandering martial artist), this may be an accurate origin. (is the story a retelling of a chinese tale?)
Techniques used in this chapter:
43.北斗百裂拳 tears target into 100 pieces
56. 二指真空把 catches an object between 2 fingers
・old man's description, page 45:

その昔・・・・・・・・・ At that time
中国より伝わる恐るべき暗殺拳があると聞く・・・ I heard of the assassin's technique, that came from China
一拳に全エネルギーを集中し Focus all energy into the fist,
肉体の経絡秘孔（ツボ）に衝撃を与え attack the body's hidden pressure points
表面の破壊より　むしろ内部の破壊を極意とした rather than destroying the surface, destruction from the interior
一撃必殺の拳法！(martial art of) Certain death in a single blow!

ＫＩＮＧ，Ｚ
Post apocalyptic biker gangs 暴走族 named after their respective leaders, members bear tattoos indicating their affiliation. description of King on page 57:
関東一円を制圧する狂暴な組織集団　The gang that controls all of Kanto (eastern Japan)

Ｃｈ１心の叫びの巻
Vocab・単語
:偵察隊 Patrol
:精巧な武器 An exquisite weapon
:Zの刺青 The tattoo of Z
:北斗の七星・・・　死をつかさどる星　The stars that govern death
:肉体の経絡秘孔（ツボ） The body's hidden acupressure points
-に衝撃を与え Land a blow
:村に居座らねえんだ　・居座る to stay (in the village)
:種モミが実を結べば・・・ ・種籾 rice seed
:いこうぜ。かかわりあうこたぁねぇ　・かかわりあうことはない This doesn't concern us
:一子相伝の暗殺拳北斗の拳 The technique, passed only from father to eldest son, Fist of the North Star
:たかがオイボひとりのためにどうしてそこまで・・・ ?
:種モミだけは実らせてほしい As long as the rice bears fruit