Days with My Stepsister
Days with My Stepsister is a Japanese mixed-media project created by Ghost Mikawa. It started with a YouTube channel created in April 2020, with its first video uploaded on May 1, 2020. A light novel series is written by Ghost Mikawa and illustrated by Hiten. The series began publication by Media Factory under their MF Bunko J imprint in January 2021. A manga adaptation by Yumika Kanade began serialization online in Kadokawa Shoten's Shōnen Ace Plus in July 2021. An anime television series adaptation produced by Studio Deen aired from July to September 2024.
Premise
After his father's remarriage, Yūta Asamura finds himself getting a new stepsister, Saki Ayase, who happens to be the hottest girl in his grade, and living together with her. Having learned the important values about man-woman relationships, seen through their parents as they carry the scars of their parents’ troubled divorces, and in order to not cause discord in the family, Yūta and Saki promise to keep a reasonable distance from each other, not to be too close or too opposing. Saki, who is longing for affection from her family and worked in solitude for their sake, does not know how to depend on others, while Yūta is bewildered at how to properly connect to Saki as his younger sister. Feeling somewhat similar, the two of them gradually feel comfortable living together. But what starts as cautious camaraderie blossoms into something deeper from shared experiences. Is it admiration, familial love, or something more?Characters
;Yūta Asamura;Saki Ayase
;Tomokazu Maru
;Maaya Narasaka
;Shiori Yomiuri
;Taichi Asamura
;Akiko Ayase
;Kaho Fujinami
;Keisuke Shinjō
;Eiha Kudō
Media
YouTube channel
While writing several works, author Ghost Mikawa learned of the existence of a reader who had a request to "deeply dig into the daily life of the characters". He was interested in seeing what would happen if he tried to write an unusual work, and decided to write a story depicting the relationship between step-siblings.Regarding the production of the videos, Mikawa is the original author of the Gimai Seikatsu storyline, but the script of the story is handled by multiple writers. According to Mikawa, the writing style of each writer is shown in each script, so it is often taken as it is.
All videos on the YouTube channel are subtitled in English, Chinese, Spanish and Vietnamese.
Light novels
The light novel series is written by Ghost Mikawa and features illustrations by Hiten. It is published by Media Factory under their MF Bunko J imprint, with the first volume being released on January 25, 2021; fifteen volumes have been released as of October 24, 2025.At Sakura-Con 2023, Yen Press announced that they licensed the series for English publication.
Spin-off
Ghost Mikawa has also worked on a spin-off, focusing on Shiori Yomiuri and his comment of each anime episode titled, Gimai Seikatsu another days. It is published by Media Factory under their MF Bunko J imprint.Manga
A manga adaptation with art by Yumika Kanade began serialization in Kadokawa Shoten's Shōnen Ace Plus online web service on July 16, 2021.During their Anime NYC 2023 panel, Yen Press announced that they also licensed the manga for English publication.