10 years after the events of xxxHOLiC Shunmuki, a melancholic Kimihiro Watanuki has taken over the shop formerly run by the mysterious Yuuko due to a promise he made to her. His companions Maru, Moro, and Mokona live together with him in relative contentment, and some familiar faces arrive every now and then: former rival turned-steadfast friend Shizuka Doumeki, and the former psychic prodigy Kohane Tsuyuri...