Ina talking about guests like this is really weird. Throughout her entire time at hololive she hasn't ever "mistaken" a day a guest was arriving and always planned around it properly before putting a schedule out. What this means is Ina didn't even know someone was arriving on Sunday until after her schedule was put up, meaning she didn't know about it happening either until Wednesday. On top of that, if it was just family or friends, she'd just mention it as she's done tons of times before.
Considering how she mentioned she might stream at a later hour tomorrow instead of just postponing things, I assumed the "guest" was actually someone looking to rent her home, as Ina is interested in moving to Japan and was thinking about renting her property.
After:
https://twitter.com/ninomaeinanis/status/1764000942687707341however, I think it's moreso a Holo-guest, since that's the part in Bocchi where she finally invites her bandmates into her home for the first time, and Ina loves being cheeky about these things to reference later. Whoever was visiting Ina tomorrow arrived early today.
Also the fact that she posted that at all raises suspicions because Ina doesn't ever talk about non-Holo stuff outside of the bare necessities to explain time off, etc.
>tl;drOff collab soon with Kiara or
someone from EN4 is visiting Ina 
