Nagi-Asu: A Lull in the Sea - Season 1 Episode 25 Love, Is Just Like The Sea.
Overview: To stall the saltflake snow and try to get Manaka's feelings back, Hikari and the others decide to do another Ofunehiki. The day before the festival, after hearing that the red sea slug pendant has Manaka's feelings in it, Akira takes it and accidentally drops it into the sea.