The Lunar Festival is the eighth chapter overall and first chapter of Higanbana no Saku Yoru ni - Dai Ni Ya (彼岸花の咲く夜に 第二夜).
On the occasion of a full moon, youkai may hold a truce for an event known as the Lunar Festival. This night is the night of a full moon. The full moon's mysterious powers help invigorate the school youkai and soothe them. Worrying about appearances, Marie is trying to change into a different attire with no avail. She finds out that youkai have a spirit anchor that serves as the basis for their appearance. These spirit anchors are usually physical objects. Higanbana's is the western doll in the School Infirmary, while Marie's is the clothes she last wore before she died. Higanbana leaves Marie, to prepare for the festival. With Higanbana now gone she uses her all her spiritual energy to change her outfit only to be nude after this attempt. She notes that she hasn't had the chance to meet the other school youkai. After Marie attempts changing her attire she ponders upon what Higanbana and Sumire would wear. After concluding her wonderment, she finally succeeds in changing to her sister's high school uniform and runs quickly to the rooftop where she is amazed by the Sakura trees coming from the underworld and full moon. No one notices her entrance except Higanbana, who comments on the clothes she is wearing. They meet the Nurse and Sakunoshin, who are drinking together. Marie feels self-conscious about her outfit, which results in Higanbana and Sakunoshin cheering her up.