Guardians 4 (ガーディアンズ4) is a Hello! Project unit put together to sing new opening themes for the anime Shugo Chara!! Doki. The unit consists of:

(光井愛佳) Mitsui Aika (Morning Musume, 8th Gen.)
(熊井友理奈) Kumai Yurina (Berryz Koubou/Kobo)
(菅谷梨沙子) Sugaya Risako (Berryz Koubou/Kobo)
(中島早貴) Nakajima Saki (°C-ute)