Oto-hime or Otohime (Japanese: 乙姫), in the Japanese folktale of Urashima Tarō, is the princess of the undersea palace Ryūgū-jō.
Oto-hime (Princess Oto)'s name consists of the character also read otsu meaning "No.
2".
[a][1] Thus Oto-hime must have been the 'second daughter' or 'younger princess' of the Dragon King (Ryū-ō), as explained by folklorist Yoshio Miyao [ja] in his bilingual edition of the In Urashima fairytale.
[1] Miyao whimsically wonders whatever became of Kō-hime, the elder daughter never mentioned.