Being still a baby, she still has short hair and is shown wearing baby clothes only.
Fruits Basket Manga
Hiro got a call from his mother that she was pregnant. Shigure made a pervy quote: "Ahh, Satsuki san, so young...". This comment made Hiro very angry.
Hinata was born sometime after the Sohmas had their summer vacation. Hiro, unable to hug her like any other proud older brother, held Hinata's hands instead.
When Hiro's curse broke, he was in the same room as Hinata, playing with her. Hiro immediately hugged her and indeed, he did not transform, meaning his curse did break. His mother comes in and gets moved and hugs Hiro and Hinata together, happy that Hiro is now able to hug anyone he wishes to.
Hinata seems to love her mother alot.
Her older Brother
Hinata gets along with Hiro very well.
- She does not appear in the anime.
- She is the only non-Zodiac sibling who knows about her brother's relation towards her.
all information on Sohma Hinata came from http://fruitsbasket.wikia.com/wiki/Hinata_Sohma