Washio Sumi is a Hero (鷲尾須美は勇者である Washio Sumi wa Yūsha de Aru?) is an illustrated novel that serialized on Dengeki G's Magazine starting from its June 2014 issue. Its story is set two years before Yuki Yuna is a Hero under a similar setting. In the story, three main characters including Washio Sumi, Nogi Sonoko, and Minowa Gin are selected as Heroes to fight against the Vertexes.
|1||Washio Sumi (わしおすみ Washio Sumi?)||April 30, 2014|
|2||Minowa Gin (みのわぎん Minowa Gin?)||May 30, 2014|
|3||Nogi Sonoko (のぎそのこ Nogi Sonoko?)||June 30, 2014|
|4||Battle (たたかい Tatakai?)||July 30, 2014|
|5||Farewell (さようなら Sayounara?)||August 30, 2014|
|6||Fairy (せいれい Seirei?)||September 30, 2014|
|7||Promise (やくそく Yakusoku?)||October 30, 2014|
|8||Friends (ともだち Tomodachi?)||November 30, 2014|
|Extra||Special Newly Written Story||December 19, 2014|
Yuki Yuna is a Hero: Washio Sumi's Chapter Edit
Main Article: "Washio Sumi's Chapter"
Yuki Yuna is a Hero: Washio Sumi's Chapter (結城友奈は勇者である: 鷲尾すみの章 Yuki Yuna wa Yuusha de aru: Washio Sumi no Sho) is the official animated version of the novel. It was separated into 3 movies (Friends, Soul, and Promise), and aired as the first six episodes of the second season of the TV anime. There are significant differences between the anime and the novel, and the movies are slightly different from the anime.
- Part of the Extra chapter was fully voiced for the mobile game Yuki Yuna is a Hero: A Sparkling Flower, titled "Sonoko's Decision".