Shank is a member of the dreaded Daluma Guild, but the terror the organization holds over the galaxy is nothing compared to that wreaked by Shank. He is bloodthirsty and cruel, feared by both the Galaxy Police and his peers. He is captain of the Daidalos, and no prisoner brought aboard his ship tends to live very long. Though sadistic enough to pass up an easy kill to instill more terror in his prey, Tarant is a survivalist and cowardly at heart, using others (even his own subordinates) as a shield when plans go awry and he has to escape.
Shank has a grudge against GP officer Seina Yamada before ever meeting him, namely because the "incompetent old man" was captured and broken by one bearing the Yamada surname in prison, tarnishing his family name. He attacks a destroyer transporting Seina and amuses himself by stalking the boy while killing GP officers. Before Shank can decide what torture to visit upon him, Kiriko Masaki steps in to save him, allowing Seina the chance to stab Shank in the arm and escape. The pirate backs down for now, vowing to hunt down and kill Seina for the shame he's brought himself. His later plans to take Seina's family hostage fail after Tenchi and the others get involved, and Ryoko Balta proves useless when she cares too much for the boy to act as an assassin. The Daidalos then leads a small fleet into a direct confrontation with Seina while en route to Jurai, but Shank is forced to retreat after coming under fire from Ryo-Ohki.
Shank has all passengers aboard a commuter ship killed, leaving a bio-droid as a sole "survivor" to be recovered by Seina's Kamidake II. The infiltration succeeds and the ship's crew is captured, with the K2 being swallowed whole by the whale-like Daidalos. Shank taunts Kiriko and Seina, gloating before returning the boy's knife to him through the chest. However, the setup itself was a ruse by the GP, with the supposed prisoners being dupes created by Washu. Off-balance, the Daidalos is mortally crippled when K2 opens fire from within the docking bay, and explodes as its captives break their way out of its hull. Tarant survives the attack, though the upper left portion of his torso and face (including his eye) are irreparably damaged. Scarred now with numerous metal accoutrements, he falls further from grace after a loss to Seiryo, upending his chances of commanding the newest flagship of the Daluma fleet.
Shank was not present when the Daluma Guild was dissolved and incorporated into the Balta Guild, instead forming an alliance with a rogue faction within the Galaxy Army. They abduct Fuku and the Kamidake II in order to learn the ship's secrets, with Tarant growing ever impatient that his scientists can't simply dissect the cabbit instead of producing imperfect clones. He's eager to fight Seina again when the boy storms his lab to take Fuku back, but Tarant is ill-prepared for the young man's rage, fleeing as he's nearly crushed by Yamada's mecha.
Bruised but not yet beaten, Shank boards the rebuilt Daidalos, commanding his and the rogue GA fleet to concentrate all firepower towards Seina, conspiring to kill him and obliterate the planet to cover their tracks. The mecha is not destroyed, however, instead teleporting in front of the two fleets and continuing its own attack. Terrified now, he sacrifices his own ships and men to buy time, ordering his crew to jump into hyperspace to escape. The ship successfully warps away just as Seina's mech comes within arm's reach, but as Shank curses the young officer for robbing him of whatever accomplishments and ambitions he might have had, the pirate is horrified to see the mecha's hand (aided with the power of the Light Hawk Wings from the Juraian tree seed powering it) reach into hyperspace to draw the Daidalos back out. The ship is crushed and dissolved to nothingness, seemingly taking its captain along with it.
Shank makes a final attempt on Seina's life on the boy's wedding day, masquerading as a butler to catch him unawares. Half-mad from further modification, Shank is fixated only on revenge and moves to slash the GP officer with his knife, promising to kill Kiriko next. However, his attack damages the floor and activates sealant gel that holds him in place, and a kick from Seina causes his trapped metallic leg to snap off. The automated devices on board detect the sparks coming from Tarant's damaged leg and seep the pirate in sealant, and no amount of curses or screams of reprisal can keep him from being fully immobilized and captured.