I Reincarnated As Evil Alice, So the Only Thing I'm Courting Is Death! Volume 3

Age Swap In Wonderland!
With Dum and Dee in opposition to her upcoming marriage to Dark, Alice decides to send the twins to boarding school to receive a proper education. But when suspicious foods labeled “Eat Me” and “Drink Me” prove too tempting to ignore, Dark and Jack end up turning into children while Dum and Dee transform into grown men. The hunt is on for the demon that laid this trap--but why is Dark suddenly giving Alice the cold shoulder? Arc Boarding School is about to become the place where secret feelings are revealed!

[From Cross Infinite World]