We won’t know if we don’t try. I don’t think there’s a point unless we struggle. Tsumugu is brimming with words of wisdom that he seems committed to living by, starting with his very upfront discussion with Chisaki in Shioshishio. Maybe too upfront for Chisaki, who is still processing Hikari’s return.
While Hikari was gone, Chisaki never allowed herself to fall for Tsumugu, so even if she really did develop feelings, she refused to fully acknowledge them; this went on for five years. Even if she’s an adult and Hikari is still a kid, he’s still there, and she still loves him, or at least a part of her does.
Miuna takes a similar but not identical tack with Hikari. She won’t deny her feelings for him, but she won’t let Hikari know about them; not as long as he’s fighting to get Manaka’s ability to love back, even if she ends up not loving him that way. But for Hikari, better for Manaka to love someone than no one.
At the end of the episode, at dawn, Hikari tells Manaka when she asks that it’s not easy to say who you love. He should know, he did it, she just doesn’t remember. Akira did it too, in the form of a lovingly-scrawled love letter. It’s the first time Manaka is faced with a confession since waking up, and she’s predictably confused.
Having been in the sea and grown an ena, Tsumugu is convinced the sea is where Manaka’s feelings remain. The sacrifice left the sea god and returned to the surface, so a price was exacted. So what if they had another Ofunehiki—the first in five years—and send another wooden Ojoshi-sama to the deep, wearing her sea slug pendant?
“Baseless and insane”, says Hikari. But they won’t know until they try. When Uroko agrees to help and everyone in his old class returns to help out (along with half of the town), Hikari starts to believe it could work; that an end to Manaka’s emotional purgatory could be nigh, and with it, the settling of a great many things.
Chisaki shows a darker side of her selflessness in an austere scene with Tsumugu in which she contemplates becoming the next sacrifice, replacing Manaka to restore the balance; Tsumugu shuts her down at once. Though she could argue that they won’t know unless she tries, one has to draw the line somewhere, and sacrificing one’s conscious life for the potential happiness of another is well past that line.
There’s a lot of gloom and angst in this episode, but also plenty of hope and optimism, most notably between Sayu and Kaname. After telling Sayu how lonely he felt after waking up, thinking no one was waiting for him, Sayu confesses to him, telling him she was. And for I think the first time on this show, someone isn’t rejected after confessing!
Kaname doesn’t agree to go out with her right then and there, but he does promise to start looking at her that way rather than as a kid, which is silly since they’re the same age now. It’s a start—a start that wouldn’t have been granted had Sayu not struggled…and tried.