Nanatsu no Ko

is a popular Japanese children song composed and written by Ujō Noguchi in July, 1921 and published in Kin no fune. Nanatsu no ko is used as the departure melody at Isohara Station in Kitaibaraki. The leader of the Black Organization uses it as his/her ringtone.

English
Mother crow, why do you squawk so? Because high on the mountain I have seven cute children. "Cute, cute," This mother crow sings. "Cute, cute," Cries the mother crow. You should behold the old nest On the mountain. And there you'll see such Round-eyed, good children.

Rōmaji
Karasu naze nakuno Karasu wa yama ni Kawai nanatsu no Ko ga aru kara yo Kawai kawai to Karasu wa nakuno Kawai kawai to Nakundayo Yama no hurusu e Itte mite goran Marui me o shita Iiko da yo

Kanji
烏 なぜ啼くの 烏は山に 可愛い七つの 子があるからよ 可愛 可愛と 烏は啼くの 可愛　可愛と 啼くんだよ 山の古巣へ 言って見て御覧 丸い眼をした いい子だよ

Trivia

 * The main number that composed the song in the series is #969#6261, which reproduces the beginning of the song.
 * The song of the name can also been translate literary as "Seven baby crows","The crow's seven chicks" or "Child of Seven".
 * The song is used as the departure melody at Isohara Station in Kitaibaraki.