Twenty-four year old Kyosuke Mizushima has just completed his first year as the lead of the sales team for Mikihara Snacks but his efforts are constantly undermined and thwarted by Shoko Abukara, lead of the marketing team and his professional rival. Their constant bickering and clashes has lead to their subordinates and coworkers referring to their battles as the birth of Mt. Kashima, born from the mixing of oil and water. Their passionate drive to undermine and defeat the other always leads to sparks flying between them as they attempt to sort out what true feelings lie beneath.