Not much is known of their relationship but Jin seemed to be aware of his brother's capabilities as he considered it amazing that Moroha defeated him. He doesn't seem to hold a grudge for his brother's loss most likely because he felt he deserved to be humbled by his loss.
The Striker Unit Edit
He and Moroha get along well. Jin was the one who recommended Moroha for a position in the Striker Units after he heard that Moroha had defeated his younger brother Gen Isurugi in a duel. Jin has great respect for Moroha's abilities which grew when Moroha defied a command and went off to battle and managed to defeat Metaphysical that was attacking innocent people.
He is Kanzaki's superior, though he holds her in high regard, Jin is often forced to punish her whenever her perverted antics get too out of hand usually doing this by squeezing her head. While Kanazaki is annoyed by Jin interrupting her fun, she nonetheless holds great respect for him which was shown when she refused to leave him behind to face a metaphysical even after he ordered her and the other members to leave the island.