いつ

How it works

The question word いつ (when) leads off the sentence, setting up “when?” before anything else. に (to) marks 日本にほん (Japan) as the destination you’re heading toward. The verb 行くいく (go) stays in plain casual form — no polite ます (polite) — and with the rising ？ (?) it becomes a relaxed “when are you going to Japan?” among friends.