Boh

"If you go, I'll cry and Mama will hear me and Mama will hear me and Mama will come in hear and kill you. Play with me or I'll break your arm!"

- Yubaba to Sen

Boh is the tertiary antagonist turned supporting character of Spirited Away. Boh is the biological child of Yubaba and the nephew of Zeniba.

Biography
Boh is a large baby that belongs to Yubaba and, up until meeting Chihiro (Sen), has remained within his nursery for fear of germs. He is treated as an infant by his doting mother Yubaba. Although Boh is a baby, he is able to talk surprisingly fluently for his apparent young age. While in his baby form, he is seen only wearing a full, one-piece bib.

During the events of the story, he is changed by his aunt Zeniba into a small grey rat. While this must have been a traumatizing experience for such a seemingly young child, a great deal of character development in his personality can be observed. Prior to meeting Chihiro, Boh is a selfish and spoiled child. He was used to getting all the attention, gifts, and food he wanted from Yubaba. He also developed a fear of germs, demonstrated by his initial hindrance in leaving his nursery. However, his personality quickly changes during his adventures with Chihiro. In his rat form, he develops a strong affiliation with Yubaba's bird, who was turned into a fly-like creature and would often carry him around when they were not riding on Chihiro's shoulder. By the end of these adventures, we see him literally standing up to his mother to help Chihiro.

It is also suggested that, prior to meeting Chihiro, Boh had not been seen walking or even standing up on his own. This is seen through Yubaba's surprise at seeing Boh standing after his return to her with Chihiro and Haku. It can be assumed that he simply became less lazy and more self-sufficient after his adventure.