Megapost on what I know.
Bujeihime, Gusari and Hitomi
A lot of information on this tale comes from three sources: An old Crane tale (
1), its Crab version (
2) and the records of the Azure Orchid (
3)
Hitomi is a child out of wedlock from a Crane and a Crab. In the arrangements for what to do with this child, it was accepted for her to be sent to the Hida. The Crane and Hitomi boarded on the ship. According to the Crane telling, the ship sank and the two of them died (1). However, according to the records of the Azure Orchid, the ship was stormed by Crab soldiers to kill Doji Bujeihime but she escaped to the shore to have her famous duel with Hida Gusari (2)(3).
Since Hitomi asks why his daddy killed her (
4), it is safe to assume that she is the child of a Crab who stormed the ship. There is nothing that proves her parents are Bujeihime and Gusari, but it is heavily implied, since Bujeihime was traveling on the ship when it sank when the Doji from the tale also was, and Hitomi's father killed her. Hida Gusari and Bujeihime were closer to each other (described as friends or lovers) (
5).
We have paintings of the two (
6). One of the figurines probably was found by Minari (
7), the other by Kio (as on Yuma's post).
The Curse
In the beach, there are ghostly armies led by a Crab and Crane bushi, believed to be Gusari and Bujeihime (
8). The time looping happened before, and only stopped when a child died. Probably Hitomi calls for sacrifices from the lineage of Gusari and Bujeihime periodically, so this curse should be happening for at least a hundred years.
Taiki said that the dog monster is not related to the curse, it is just here because the seas were stirred.
The Kuni said that there must be an object that is linking the spirit to this realm. The object must be destroyed in order to set the spirit free (and end the curse forever). (
9). This object may either be the two figurines (5) or paintings of the two (6).
But there is also a theory that says that the object and the spirit need to be reunited before it is free (same topic).
One of those is probably like to draw combat (
(10)). I would like to meet Gusari and Bujeihime first before taking decisions. Either we try to reunite the three ghosts (peaceful resolution to the curse) or break the objects that are making the three stay on this realm. I want to try to reunite them first. We may convince either of them on the suffering of the child. But Gusari seems to be the pragmatic sort, so maybe we can argue that it is necessary for the war to end, and the war is taking resources that could be used on the wall.