Consider these stanzas taken from the opening song of Aria the Animation: Undine.
An Undine as a mythical concept is a female water spirit or nymph. In the anime "Aria", they are what gondola operators are called. (In layman terms they are boat rowers)
Vocative case: the case used for a noun identifying the person or thing (animal, object, etc.) being addressed.
さあ 漕ぎ出そう 光る波へ
笑顔が すぐ こぼれる (Come, let us row towards the shimmering waves, our smiles will soon overflow.)
ねえ 伝えよう このときめき (Hey, let us impart the feelings of our beating hearts. )
ウンディーネ(Riding the wind, I will return to you
as an Undine.)
さあ 漕ぎ出そう 遥か未来へ
水面に 夢 広がる (Come, let us row towards that distant future; our dreams will spread out over the water.)
ねえ 見つけよう まだ知らない
宝物を あなたと一緒に (Hey, let us discover yet unknown treasures.)
ウンディーネ(Together with you
I disagree with translation in the highlighted parts above.
(Question) Can it mean "Riding the wind, I will return to you,
my Undine" and "Together with you,
my Undine"? Treating
ウンディーネ as vocative case?