Yako Gureishi is a Japanese manga creator, known for the fantasy series Somali and the Forest Spirit as well as the work Kojirase Holic. Gureishi is the sole author and artist of Somali and the Forest Spirit, a manga that was serialized online from April 2015 to October 2019 in Tokuma Shoten's Web Comic Zenyon magazine. The series was collected into six tankōbon volumes.

The story of Somali and the Forest Spirit is set in a world where humanity has been hunted to near extinction. It follows a golem, a forest spirit who lacks emotions, who finds a young human girl named Somali. The golem decides to protect Somali and help her find other surviving humans, and the narrative focuses on the bond that develops between them as they travel through a richly imagined fantasy world. Gureishi's artistic identity in this work is characterized by an ornate visual imagination and a blend of wonder with occasionally creepy or haunting imagery. The artwork features lush nature scenes and creative creature designs, which has led to the series being described as part of the iyashikei, or healing, genre of character-driven stories.

An anime television series adaptation of Somali and the Forest Spirit was produced by the studios Satelight and Hornets and ran for twelve episodes from January 9 to March 26, 2020. The series was co-produced and streamed by Crunchyroll. However, Gureishi has publicly expressed significant regret and frustration with the anime adaptation. Due to being occupied with hectic manga deadlines, Gureishi was unable to provide adequate supervision for the anime's production. One specific point of contention was the mispronunciation of the character Somali's name in several episodes, a mistake that was not corrected before broadcast. Gureishi has stated that they cannot watch the anime adaptation as a result of these issues.

The Somali and the Forest Spirit manga experienced a long hiatus before officially concluding on December 22, 2020. This conclusion was attributed to Gureishi's health problems. Furthermore, Gureishi has spoken openly about the circumstances surrounding the manga's cancellation, claiming that the publisher, Comic Zenon, chose to end the series to focus on contemporary stories rather than fantasy. This experience has led Gureishi to become a vocal critic of certain practices within the manga and anime industries. Gureishi has stated that creators are often treated as commodities and that many are ostracized unless they produce bestsellers, and has expressed a firm commitment to changing the plight of manga artists so they are no longer treated as expendable resources.