"누구를 방문할 거야?"

Translation: Who are you going to visit?

[Shlomo_]

"Whom" is correct, "who" is not.

[Jeong-JinL]

Both are correct.

[MatthewEpp5]

Agreed. It should be the accusative case, not the nominative case. Although in spoken English, we will rarely hear whom and almost exclusively hear who.

[Jeong-JinL]

There is no accusative case in Modern English. Technically it's called the objective or oblique case as there is no formal difference in how words are marked if they are any kind of object whatsoever. I don't think you can get fewer cases than the 3 total in English.

[Devina842083]

How to say 'Who are going to visit us?' ?