The Capriccio of Maiden's Mind

Kazuki overhears Hino muttering about Yunoki and her and he thinks they are getting married. Actually, Yunoki told Kahoko about a fiance "candidate", Ayano, and how she was being too persistent in chasing after him. Azuma lied and told her someone else was in his heart, and asks Hino to pose as his "love".

Synopsis excerpt via Kitsu.