After-School Bitchcraft Series by Yu Shimizu

Science teacher Renji Fuyumi is secretly a sorcerer, but after his barriers are accidentally broken by the fashion-obsessed Ririka Kirise, he decides to make her his disciple. Looks can be deceiving in this titillating tale of the occult!

While Renji continues to train Ririka, he’s visited by none other than Berta Mathers, his former pupil and a member of the Sorcerers’ Association! She’s come to keep an eye on him, and when she finds him dabbling in forbidden magic…she’s more than ready to teach him a thing or two. But they’ve got bigger problems, as one of Berta’s colleagues catches Ririka alone and attacks her! Will Renji and Berta make it in time to save her?

When new student Elina transfers into Class C, Ririka can’t help but notice how similar they are. And when she starts hanging out with all of Ririka’s friends, it becomes obvious that Elina’s trying to replace her! Little does she know that her new classmate is actually a fellow sorceress, and she’ll need the help of all her friends to take down this powerful witch!