During the latest chapter Yamato’s face is finally shown and is revealed to be a woman.
Over 20 years ago, Yamato went to her father Kaido and told him that she wanted to be the great samurai Kozuki Oden, resulting in Kaido beating her. Yamato was present during Oden’s execution in the Legendary Hour, and became very sorrowful at the samurai’s death.
Later, Yamato found Oden’s logbook in Kuri and held onto it dearly while starting to emulate everything about Oden. Yamato began presenting as a man to emulate Oden’s gender, and has since been widely referred to as Kaido’s son.
Yamato greatly admires the legendary samurai Kozuki Oden above anyone else, to the degree of emulating every aspect of him including his appearance, goals, and even his gender. Thus, Yamato wishes to fulfill Oden’s dream of reopening the borders of Wano Country.
This attachment to Oden puts Yamato at great odds with her father Kaido, who is an enemy of Oden and his family. Although Yamato and Kaido are not indicated to be enemies, Yamato has acted against her father and his crew to achieve her goals, such as attacking Ulti in order to take Monkey D. Luffy from her, and wishing to work with Luffy, another enemy of her father, to achieve Oden’s goal.
Yamato is a very powerful warrior, with Black Maria noting that bringing her back to Kaido’s fortress after she had left would be a difficult task.
She possesses monstrous strength resembling her father’s, being capable of wielding a large and heavy kanabo and using it to defeat Ulti, an Ancient Zoan user and one of the Tobiroppo, with just one blow.
Furthermore she was able to physically match Luffy’s strength with relative ease, even when the pirate increased his strength exponentially with Gear Second and Gear Third.
Kaido and Yamato have a strained relationship, as Yamato idolizes Kaido’s enemy Kozuki Oden. Although Kaido disapproves of her idolizing him, he does refer to Yamato as his son for unclear reasons.
Kaido’s overall view of Yamato is unknown; he has called her an “idiot”, though wishes to have her participate in his party during the Fire Festival.