Takeshi Kovacs turned to for help in Altered Carbon season 2, also appears in Altered Carbon: Resleeved. Not only that, we get to see how the strong relationship between the two characters began.
Based on the books by Richard Morgan, Altered Carbon is set in a future where humans have discovered a way to digitize their minds and store them on disks called cortical stacks, which are inserted at the top of a spine. If a person's body is killed, their stack can be recovered and put into a new "sleeve," creating the potential for immortality. Altered Carbon: Resleeved is an anime feature spin-off of the live-action series, which follows Takeshi Kovacs in his early years as a mercenary for hire, who himself is on the run from the authorities.
In Altered Carbon season 2, Takeshi reluctantly returns to his home planet, Harlan's World, and seeks out his most powerful there: Tanaseda Hideki. The head of the Tanaseda yakuza clan has a long history with Takeshi (seriously - they first met more than 280 years ago). When they meet again, Hideki explains to his great-grandson that Takeshi carried out a job for him after the fall of Stronghold, and that after Takeshi was caught and tortured by the Protectorate "in every way they knew how," he still never gave Hideki up. Significantly, Hideki once recited his family's death poem to Takeshi, making him perhaps the only person outside of the Tanaseda clan to know the poem.
In Altered Carbon: Resleeved, we get to see the first meeting between the two characters. Takeshi is carrying out a mission for Hideki, investigating his brother's death within the Mizumoto clan on Latimer, in exchange for Hideki using his influence on Harlan's World to wipe Takeshi's record there. Hideki suspects foul play within the Mizumoto clan that's somehow connected to their sacrificial ceremony, in which power is handed over to a new leader. By the end of Altered Carbon: Resleeved, Hideki discovers the terrible truth about what happened to his brother - thanks to Takeshi.
The end of Altered Carbon: Resleeved reveals Hideki's more conniving side, as he tells Takeshi that he hasn't even begun to make moves on wiping his records on Harlan's World. First, he wants Takeshi to carry out another mission for him. If Netflix may well produce more anime spin-offs as a follow-up to Resleeved, and perhaps even reveal the circumstances that led Hideki to recite his family's death poem for Takeshi.