Hello. I have a question, hoping someone can explain the grammar of two sentences in lesson 2.9 talking about what will happen. The first sentence is ashita testo ga arimasu. I understand what it says but I wonder why there is no WA after ashita? Can someone explain why WA is not used? Also the next sentence shuumatsu NI matsuri ga arimasu. Once again I understand what it says and why using NI (as that it is marking the time/when) but it makes me feel ashita is somewhat also marking a time/when. So why the particle with the second sentence and not the first sentence?
Thanks