The big adventures and discoveries in the last episode give way to a quieter, more introspective episode focusing primarily on Chisaki, who was mostly absent from all that. The episode explores her thoughts and her heart as thoroughly as the others explored Shioshishio.This leads to some beautiful, touching, and often hilarious scenes with her alternating between the childhood and adulthood.
By all appearances, she the nurse and Tsumgu the researcher are a married couple, and Kaname is like their sour-faced kid who bristles when Tsumugu explains the pragmatic approach to everything that’s happened. Chisaki the Adult takes Tsumugu’s side, and Kaname excuses himself, making a snide comment about how much she’s grown up. This leads to her breaking out her old school uniform (once cute, now sexy) and pouring herself into it, a deeply funny private moment that both guys invade when they hear her slip and fall.
Chisaki also see that Miuna likes Hikari too, from the look in her eyes as she eavesdrops on Hikari talking to the still-slumbering Manaka, the bomb that will restart time if and when she awakens. Chisaki can’t not see her past self in Miuna, feel the futility and pain of not being the one. Between that and the result of trying on her old uni, she decides to pivot back to adulthood, insisting Tsumugu ply her with plum wine. Things get loose but never amorous, and she dozes off before Tsumugu and state an important truth.
That truth is that he has filled the space left by Manaka for five years with Chisaki, which is what people do when they lose things in the transition from childhood to adulthood. Because he was able to do it, he’s sure she can too, if she takes the next step. Part of her back-and-forth this week is due to her realizing she’s the age Akari was when she had to decided between the sea and her love, mirroring the continuation of the Ofunehiki she hears from Tsumugu’s gramps.
The rest of the story is that the sea god and surface girl are happy for a time, but she grows depressed and restless because her true love is still on the surface. The sea god finally allowed her to return, but in exchange for something—likely her ena—and sure enough, Manaka’s shattered. But when Hikari saves Chisaki from getting lost like he did years ago, she also realizes she still likes him. Nothing harder than growing up when the gaps you’re expected to fill with new things are still occupied by the old.