When an act of terrorism threatens Japan's largest underwater research lab, Masamune and his team are called in. Down in the Pacific Ocean they find love, betrayal, and danger as you have to watch your back, both in and out of the water.

With a baby on the way, Misaki faces her next troubles: Akihiko's family. Sudden appearances from different members has Misaki questioning if having a child is the right thing to do. And let's not forget her brother. "YOU KNOCKED UP MY SISTER?"