Kenshiro's initial adversary in the series, Shin was Kenshiro's friend and rival, who was taught in the martial arts style of Nanto Seiken, specifically Nanto Koshuuken (南斗孤鷲拳) or "Lone Eagle Fist of the South Star", whose practitioners are able to pierce flesh with their bare fingers.

He had secretly fallen in love with Yuria, Kenshiro's lover and had slowly become insanely jealous. Jagi soon corrupted Shin, and convinced him to take Yuria for himself. Shin promptly challenged and defeated Kenshiro, then tried to convince Yuria to love him by wounding Kenshiro with his fingers, giving Kenshiro his distinctive seven scars in the shape of the Big Dipper. When Yuria finally gave in and said she loved him, Shin left Kenshiro for dead in the desert.

Shin went on to amass an army to steadily conquer the land, under his flag of "The Bloody Cross", in an attempt to fully win Yuria's love. Ultimately, in her honour he built the city of Southern Cross. However Yuria, because of Shin's cruelty and ruthlessness, and her love for Kenshiro, never gave Shin her love.

However, Kenshiro survived, and wandered the desert in search of Yuria. When he finally came face to face with Shin in the city of Southern Cross, he defeated Shin with the Hokuto Juuji Zan (北斗十字斬) or "Cross-Kill of the North Star", to kill Shin with his "Bloody Cross" emblem marked on his chest. However, Shin confessed that Yuria had seemingly leapt to her death and, preferring to die by his own hand than by Kenshiro's, followed her down.

Kenshiro took Shin's corpse and gave him a proper burial, saying that it was "because he loved the same woman as me".