Koi to Karada no Kyoukaisen恋とカラダの境界線 ; Border of Love and Body ; Love and Body's Borderline ; Love Workshop

Right after he was dumped, Tarou got a call from his newly-wed older sister, asking him to babysit her husband's teenage son. Tarou arrived to find a disrespectful 17-year-old kid who seemed to hate his guts. How would Tarou cope with the situation?