Moon Lovers: Scarlet Heart Ryeo Episode 12

When a total eclipse of the sun takes place, Go Ha Jin is transported back in time to the start of the Goryeo Dynasty of Korea during King Taejo's rule. She wakes up in the body of the 16-year-old Hae Soo and finds herself living in the house of the 8th Prince Wang Wook, who is married to Hae Soo's cousin. She soon befriends several of the princes and meets the ostracized 4th Prince, Wang So. Although knowing she should not get involved in palace intrigues over the succession to the throne, she inadvertently becomes a pawn in the struggle, as several of the Princes fall in love with her.