Lishka is the deceased daughter of Tasya. She's first introduced in Book XVIII: The Moon of Portia's route during a flashback, although her form is glitched and obscured. Her actual appearance is revealed during Book XX: Judgement, specifically in the Reversed path.
Little is known about the specifics of Lishka's life, with the only sources of information being Tasya's words and memories. According to Tasya, it seemed that Lishka had a happy childhood with a loving mother. When Tasya started up her naval trading business, Lishka would find herself coming along with Tasya and her crew, and seemingly enjoyed it.
In the early stage of Tasya's business, Liskha was on another of these trips when a storm hit them and threatened to capsize the boat. She ran belowdecks to hide, while her mother stayed on the deck, praying to be saved. She was answered by a demon, who promised to calm the storm in exchange for the first thing she saw when she went belowdecks. She agreed, deciding to go straight to the cargo room, but on her way, Lishka ran up to her, happy to see her alive, unknowingly marking herself as the price for the demon's power. Her mother refused to give up her daughter, which angered the demon, and because her mother broke her deal, she unleashed a storm on herself, that would follow wherever she went, and while she would be able to run away for the moment, that would prove to be a temporary solution.
Some time in the future, Lishka was aboard a ship on another of her mothers business routes, playing with a much younger Julian and Portia. The magical storm caught up to their fleet and was later described as worse than naturally possible, and Lishka somehow became trapped in ropes and netting on the deck in trying to find refuge belowdecks. She cried out for her mother to come save her, but before Tasya was able to reach her, she was washed overboard and died.