Nagi-Asu: A Lull in the Sea

Detritus (1x24)

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Tsumugu dives into the sea after Chisaki. He starts having trouble breathing and is about to lose consciousness, but then suddenly gains Ena. Tsumugu finally catches up to Chisaki and lets her know his feelings while they're in Shioshishio. Chisaki cries and runs away.