During the entertainment district arc in the Demon Slayer: Kimetsu no Yaiba anime, it is revealed that Gyutaro was living inside Daki’s body, but why did he decide to do that anyway?
After all, why was Gyutaro living inside Daki’s body in the Entertainment District Arc of the Demon Slayer: Kimetsu no Yaiba?
Despite the fact that they were demons, Gyutaro loved his sister and wanted to protect her at all costs. Therefore, as a demon, he decided to share a single body with her, and then live inside Daki for much of the time.
This makes him able to protect her efficiently since they wouldn’t be able to kill her just by cutting off her head, as was shown when Uzui Tengen was able to cut Daki off easily. So when they cut off her head, he would emerge to easily save her from the threats that appeared.
The manga version of Demon Slayer: Kimetsu no Yaiba was already finished, while the anime adaptation is still ongoing, with Season 3 being teased in the final episode of the Entertainment District Arc anime.