二階堂 藍

Likes: Yuuma, bikes
Dislikes: Nothing
Favorite food: Miso soup
Dislikes food: Bitter foods

Shinku's twin sister. She never leaves someone alone if she finds that the child is in trouble. Always has a smile on her face. Her specialty, or belief, is to bring a smile to someone's face. Quite energetic, despite her petite body. She's in love with her childhood friend Yuuma.

Nikaidou Ai (along with Nikaidou Sora) are actually two parts of the soul of the "original" Haku who was the mother of the Ren who took Kanoue Yuuma's name. Ai's soul is the continuation of Haku's soul after leaving her bad memories behind and reincarnating.