Yaegaki Hime

This is an entry for a contest in "real world".
It's about Princess Yaegaki, the protagonist of an interesting Japanese tale.
I didn't find it in English, so I translated the story from a website: (I hope it doesn't have too many mistakes)

"While in the middle of civil wars in XVI century in Japan, shogun Ashikaga Yoshiharu was murdered in Kyoto on 1550. The widow asked the two most powerful clans, Takeda and Uesugi, to find the murderer in a three years time, or else they would pay by handing over each clan's firstborn child: Takeda Katsuyori and Nagao Kagekatsu.

As the time went by before they caught the killer, Katsuyori fell in love with Uesugi clan chief's daughter, the gorgeous princess Yaekagi, although her family had stolen a precious helmet from clan Takeda, which was said to hold a fox's spirit.

However, the deadline ends and no member of both clans finds the murderer, so each clan's firstborn child is required to go to the castle and pay with their heads. When the messenger who goes to Takeda clan meets Katsuyori, he fakes a suicide (a faithful samurai friend prefers to die instead of Katsuyori) and hides his identity by dressing as a gardener and changing his name into Minosaku. Later he's hired in Uesugi's house, so he gets to see his beloved princess and the chance to recover his clan's helmet.

Yaegaki is suffering, and can't stop looking her beloved man's portrait. But then, one day, she catches a glimpse of the gardener and realizes he looks exactly like Katsuyori. In a certain moment, he comes into her room and explains what happened, so she stays calmed and happy.

Nevertheless, Yaegaki's father also realizes the gardener's manners aren't those of a gardener, so he asks him to deliver a message, and sends two of his men to follow him and kill him.

Yaegaki finds out about the plan, so she tries to catch up with Katsuyori, but it's already night, and her loved is on the other side of the lake Suwa, which is frozen, so she can't use a boat. Hopeless, she rushes to the shrine next to palace, and prays, as she looks at Takeda clan's helmet. Yaegaki takes it in her hands, goes outside and stands before the lake. She suddenly sees a reflection of a ghostly fox in the water, and realizes it's the helmet she's holding. Just then the fox's spirit appears before her and promises to help her save the boy.

Then (this is one of several versions), she holds the helmet high, and a group of fox's spirits appear, take her into the air, and fly her across the lake.

She arrives just in time to save Katsuyori's life."