Hikari Tanaka, who was stranded at the sea a year ago, was rescued at the bottom of the ocean by the "King of the Deep Sea" and returned as a deep-sea girl with deep-sea monster skills!
Yamada Takeru, Hikari's childhood friend, is delighted to see her return, but is perplexed by Hikari's peculiar biology, which causes her to glow and appear translucent. Takeru, who still has feelings for Hikari, attempts to accept her, but...Still, he would like to accept Hikari.

Note: This series is unrelated to the vocaloid song of the same name.