First movie of Magical Taruruuto-kun

Kanon spin-off OVA bundled with vol. 22 of the Kami nomi zo Shiru Sekai manga. (Source: Weekly Shonen Sunday)

Ayumi Mamiya is a witch cursed to lose her powers and only one boy can break the spell. Haruo Yoshikawa thinks he is a normal boy but unknown to him his three sisters have magical powers and keep him protected and ignorant about the existence of magic. Now Ayumi must wake up Haruo's latent powers to save herself but his sisters will have none of that. (Source: ANN)

Shiratori Ryuushi is a young artist-in-training, about to start studying at a vocational school. Arriving at his new lodgings, Narutakisou, he finds himself the focus of attention for the collection of weirdos that inhabit the place. He also meets and falls for the landlady, Aoba Kozue, who seems to be both lovely and charming. However, Kozue is not what she seems to be... in fact, she's more. (Source: ANN)