Kokushibo and Douma were secretly dating. Koku is Upper moon1 while Douma is Upper moon 2. Their demon king, Muzan has a crush on Kokushibo but didn't know he was dating Douma. Everytime the two would hang out, Muzan would get angry and jealous that Koku was hanging out with Douma instead of him. One time, Kokushibo was braiding Douma's long platinum blonde hair in his room when Muzan barged in without knocking, seeing both of his demons together and it triggered his jealousy and anger.