Baby 5 and Don Sai met on the battlefields of Dressrosa during the battle between Straw Hat and Donquixote Doflamingo.
Because of her abandonment problems, Baby 5 has always sought company even in the middle of a battlefield. It was quite difficult as Doflamingo was killing the inhabitants of Dressrosa. Numerous failed assassination attempts from Baby 5 to Doflamingo, culminating in the duel of Sai and Baby 5 in the dressrosa arc.Baby 5 initially fought Sai in Dressrosa because he was on opposite sides. During her struggle with him, she had a misunderstanding in which she interpreted her words as a series of romantic jokes. In his opposition to her tendency to do everything that is asked of her, he told her to kill herself. She almost did, but he quickly stopped her despite Don Chinjao having told him to let her do the deed. He had tried to prevent Sai from saving Baby 5, but after Sai had unlocked the haki during Don Chinjao's attack, he uses it and puts Don Chinjao out of commission.Soon after, Lao G challenged Sai in an attempt to thwart the alleged proposal. Realizing that she had spent her life feeling useless, he promised to make her his wife if he won, to her great joy.After a tough battle, Sai manages to defeat Lao G and Baby 5 has conceded, sealing their engagement. Although they initially fought against each other in Dressrosa, Baby 5 fell in love with Sai. Baby 5 rejoiced at this news and after Sai's victory, she began to refer to Sai as "dear" to the latter's great regret. After breaking off his engagement to Uholisia, he officially married Baby 5, making her his wife
