Cardcaptor Sakura, Gakkou no Kaidan Recommendations
Gakkou no Kaidan is the horror version of Cardcaptor Sakura.
Two girl protagonists who lost their moms when they were very young encounter the supernatural during the school and have to fight it with a creature that guides them on how to do so. Sakura is the cute and childish version of the story, with Sakura catching all the Clow Cards, and Gakkou no Kaidan is the scary version with Satsuki putting all the dangerous ghosts into spiritual sleep.
Both series revolve around phenomena that managed to escape from their seals and must be sealed again.