Ep. 3: Hikari learns about the village's strict marriage rules and the consequences for children born with surface partners.

Akari faces her father's anger for breaking village rules, while Hikari recalls caring for him after their mother died. Akari then announces her decision to end her relationship. The following day, Hikari tracks Akari's boyfriend to Tsumugu's home, where Tsumugu's grandfather intervenes. He explains that villagers cannot marry outsiders because their offspring lack ena, making underwater survival impossible and forcing families to leave Shioshishio. Hikari realizes Tsumugu's grandfather also originates from the village. Consequently, Hikari drops her hostility toward Tsumugu, and the group bonds after completing their offering. Seeking to resolve Akari's distress, Hikari attempts to reconcile with the boyfriend but is intercepted by two girls who previously fought him. One reveals that the man is her father, halting Hikari's efforts.

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