Author Bow Ditama of the manga Kiss×Sis revealed some news. According to him on Twitter, the last two chapters of the manga are being finalized.
Therefore, we do not have a confirmed publication date.
Synopsis:
Keita Suminoe is a senior in elementary school who lives with his father, stepmother, and two older twin half-sisters, Ako and Riko. Since their parents' second marriage in childhood, the siblings have felt a deep affection and solidarity towards one another.
Kiss x Sis was serialized in Bessatsu Young Magazine in December 2005, concluding in Monthly Young Magazine in December 2009.
Finally, Kiss×Sis received a 12-episode OAD series between 2008 and 2015 and a 12-episode anime series that aired from April 4, 2010 to June 21, 2010.