Ring Finger Princess(2007)

Kusuriyubi Hime

Houjou Hinaki is a young girl who has in her possesion a ring, a gift from her father. Anyway, this ring is not an usual one. When she kisses it, a young noble man named Sae appears in front of her and grants all her wishes. However, Sae is trapped in the ring and can't rezist much time outside and together with Hinaki and her freaky school mate Yume-senpai, tries to find out a way of how he can escape from the ring's prison.