The Witch's House:The Diary of Ellen, or simply The Diary of Ellen, is a manga based off the original The Witch's House: The Diary of Ellen novella.
The manga is published by Kadokawa in Japan and Yen Press in the United States.
Just like the novella its based off of, the Diary of Ellen manga follows the titular protagonist Ellen and her origins prior to the events of The Witch's House.