Higurashi When They Cry: Cotton Drifting Arc, Vol. 1 - manga

You've already met Keiichi Maebara and his mischievous friends in the Abducted by Demons Arc. But Oyashiro-sama's curse is poised to strike anew in Hinamizawa village. When Keiichi spots tomboy Mion working at a maid café, he can hardly believe his eyes! But it's not Mion after all - it's her identical twin sister, Shion. Keiichi's never heard of this "twin sister" before and suspects it's just another one of Mion's pranks. But through Shion, Keiichi is able to see a quieter, more feminine side of his best friend, even if it is all an act. As Keiichi spends more time with Shion, however, Rena grows more accusatory...