Three People and Two Pearls

Overview

When Kenji, Nanami, and Hikari were kids, they found an oyster with 2 pearls in it. It was decided that Hikari would keep the pearls since there were only two of them. Back in the present, Hikari has enrolled in Kenji's school, causing trouble for him. On top of that, she has begun diving more, but what is she looking for?