The final volume, simply titled Hentai Ōji to Warawanai Neko. 12 , opens with Tsukiko still asleep. Yōto has gathered all the key players—Tsukushi (his classmate, no relation), Emi, and even the Cat God herself in a temporary human form. They stand around Tsukiko’s bed as the cherry blossoms fall outside the hospital window.
Based on the title provided, Sleeping Cousin -Final- appears to be a conclusion or special chapter within a doujinshi or adult manga series by the circle or artist (also known as Hen-Neko or Hentai-Neko). Sleeping Cousin -Final- -Hen Neko-