Long, long ago, when the waves were still full of fish in the territories of Kirigakure, there was a fisherman. His name was Oss Kimedo, a non-assuming man, who was still young and in his prime. He didn't do much, and lived in a cabin near the ocean, where he'd fish for his own fish sometimes, and would sell the left over fish. He was relatively poor, but that didn't stop him from fishing like he loved to do. Until one lucky day he found a gift of Gyuki himself. As luck would have it, Gyuki got one of his horns cut off in an assault, unknown to Oss at this time was that A, the Raikage, had cut off the horn. As he pulled up his net, he saw that the horn was stuck in it, glowing purple. Not realizing what it was, he took it home, where he more carefully examined it. In this period of time he held the horn up to his head, perhaps as a result of a vision he received telling him to do so. The horn became attached to his head and slowly integrated with his skull, disappearing and then re-appearing as two horns on the side of his head. This would be the birth of the Osuushi clan, as he renamed himself after his new likelihood - that of an Ox, like Gyuki was.
Gyuki, the horn missing Following that, the powers of Gyuki flowed through him. Not like a pseudo-jinchuuriki, obviously, as he had no natural shinobi powers. Merely his chakra multiplied a lot, and he became a lot more capable physically. Despite having the perfect chance to adapt to a shinobi lifestyle, he chose not to, instead erecting a shrine in the name of Gyuki in his house. Over the course of time, his offspring also gained horns, and so the Osuushi clan grew, and so did the house.
Slowly it became a temple with a large shrine of Gyuki inside it, the tailed beast being revered as the source of power for the Osuushi clan members. Some artifacts made it's way to this location, some being
'given voluntarily' while others were gifted by passer by's who held some sort of relevant article to Gyuki.
This posed an interesting question as they were frequently assaulted by vagabonds, who tried to steal these artifacts. Using the power given to them by the eight tails, they managed to defeat these vagabonds time and time again, which was proof of their strength despite not being shinobi's.
Their service continued until 11 years ago, when their service was swiftly ended with the arrival of covert forces, which were suspected Hamajo Confederate Loyalists, who ended the lives of all those in Kirigakure. As the shrine was on the outskirts of Kirigakure, they had some time to react, but stubborn people of the Osuushi clan predicted that Gyuki would defend them, which was true to a degree.
Using their natural power, the veteran shrine maidens and keepers were capable of defending themselves against the initial patrols of the attackers, which weren't quite the capable soldiers that could defend against untrained, but very strong and zealous defenders of Gyuki. However as more Osuushi fell, the elderly were left to defend themselves, and naturally that didn't go so well. Senhime was the sole survivor, it seemed, only due to her natural shinobi expertise. She grabbed Akumako, and made a run for it, luckily escaping the shinobi with the usage of her jutsu.