While kita (北) means north, the kita in your sentence is 来た, the past tense of kuru (来る), to come. Doesn't your book have kanji? There are a lot of homonyms in Japanese. "no wa" is a nominalization, it changes the "came to Japan" to a noun. "Came to Japan" is trip? = 日本に来たのは旅行ですか。 "Did you come to Japan to travel?" sounds a bit weird to me, as if you're going to travel to somewhere from Japan, instead of the "is this a trip?" feeling of the Japanese sentence... maybe I'm just bad at English.

"Nowa" comes after a clause with a subject and a verb where the former is always in "ga" form not "wa", suggesting the reason behind the subject's action. "No" turns the clause into a noun chunk and "wa" indicates its subject status in the entire sentence. The reason behind your coming to Japan is sightseeing(ryokoo)? Good luck with your Japanese lessons. spring