The chemistry between Seeun and Yoon, the loudest combination in STAYC, started a long time ago.
* In 1111, the 'Papyeong Yoon' clan built the tomb of their ancestor in Paju. King Yejong decided on the location.
* In 1614, the 'Cheongsong Sim' clan was granted land in Paju and used it for the tomb of the Chief State Councillor.
* In 1763, the Yoon clan dug up some of the Sim clan's tomb area, and the dispute grew bigger.
* King Yeongjo exiled the leaders of both sides, but the dispute did not end and the conflict continued into the 20th century. They fought in court, brought excavation tools during ancestral rites, and built a wall around the tomb.
* In 2006, the Yoon clan bought nearby land and gave it to the Sim clan, and the Sim clan agreed to relocate the tomb.
* At the end of February 2024, 'Papyeong Yoon' clan's Yoon Seeun and 'Cheongsong Sim' clan's Sim Ja-yoon watched the movie 'Exhuma'. This movie is about digging up graves. Although some records describe Yoon Seeun as belonging to the Namwon Yoon clan, it was historically merged with the Papyeong Yoon clan’s Namwon Baek branch.