Fist of the North Star - Season 1 - Eps 4: Attack the Bloody Cross! The Secret Technique, Death by Soft Strikes.
Ken learns that the prisoners that were transported with Rin were taken to a prison camp in a nearby valley. Ken manages to break the imprisoned villagers free, but during their escape they're all slaughtered in an ambush led by Mr. Heart, the last of the Four Jacks. While Heart's excess flesh proves resistant to his attacks, Ken eventually uses a techniques which penetrates through his body. From his battle with Heart, Ken learns an important clue which reveals to him the identity of King.
About Fist of the North Star

Title: Fist of the North Star
First Air Date: 1984-10-11
Last Air Date: 1988-02-18
Status: Ended
Rating: 8.15/10 (from 107 votes)
Language: JA
Seasons: 7
Total Episodes: 152
Network: Fuji TV
Genres: Action & Adventure, Animation, Sci-Fi & Fantasy, Drama
Production Companies: Fuji Television Network, Toei Animation, Shueisha
Synopsis
In the year 199X, human civilization has been all but destroyed by a nuclear holocaust.
Cast

Akira Kamiya
Kenshiro (voice)

Takeshi Aono
Rihaku

Koji Totani
Jagi

Kaneto Shiozawa
Rei

Yusaku Yara
Dagarl

Banjo Ginga
Souther

Takaya Hashi
Toki

Yuriko Yamamoto
Yuria

Toshio Furukawa
Shin

Daisuke Gori
Uighur