わに

How it works

の (of) links two nouns to show possession: わに (crocodile) + の (of) + 口(くち) (mouth) means "the crocodile's mouth". は (topic) then raises that whole phrase as the topic — "as for the crocodile's mouth…". The adjective 大きい(おおきい) (big) ends the sentence on its own; い (い-adjective)-adjectives don't need です (is) in plain speech.