Gunjō ni Siren (Japanese: 群青にサイレン, Hepburn: Gunjō ni Sairen, "Ultramarine Siren") is a Japanese baseball-themed manga series written and illustrated by Mikan Momokuri.

Written and illustrated by Mikan Momokuri, Gunjō ni Siren was serialized in serialized in Shueisha's jjosei manga magazine You from July 15, 2015,[1][2] to October 15, 2018, until the magazine ceased its publication.

[3][4] It was later serialized on Shueisha's online platform Shōnen Jump+ from February 2, 2019,[5] to August 3, 2020.

[6] Shueisha collected its chapters in 12 tankōbon volumes, released from November 25, 2020,[7] to October 2, 2020.

[8] The series ranked third on AnimeJapan's "Most Wanted Anime Adaptation" poll in 2019.