Might be something else. The Utsuro-bune had a fish eggs motif. The panel at the end of the chapter looks exactly like the barnacle-encrusted box from
chapter 13.2.
Back in
chapter 6.1 (the Utsuro-bune arc), Inubousaki said, "Well... As far back as I can remember, I've never liked bein' near water.", which is quite concerning now that she's suddenly saying she wants to go to the sea. Azuma said in this chapter, "This is only the beginning. More sinister events will follow...". And Gerai just suddenly woke up. So it looks like whatever has been possessing Inubousaki, as well as other entities, might also be waking up.