Days with My Stepsister

Days with My Stepsister (義妹生活) 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 premiered in July 2024.

Premise
After his father's remarriage, Yūta Asamura finds himself getting a new step-sister Saki Ayase, who happens to be the number one beauty of her grade, and lives together with her. Having learned the important values about man-woman relationships, seen through their parents, 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 her older brother. Feeling somewhat similar, the two of them gradually feel comfortable living together.

Characters

 * Yūta Asamura (浅村 悠太)
 * The protagonist of the Days with My Stepsister series. He is Saki's step-brother and a second-year high school student. He works part-time at a bookstore.
 * The protagonist of the Days with My Stepsister series. He is Saki's step-brother and a second-year high school student. He works part-time at a bookstore.


 * Saki Ayase (綾瀬 沙季)
 * The female lead of the series. She is Yuta's step-sister and a second-year high school student.
 * The female lead of the series. She is Yuta's step-sister and a second-year high school student.


 * Tomokazu Maru (丸友 和)
 * Yuta's friend at school. He is a member of the baseball team and an otaku.
 * Yuta's friend at school. He is a member of the baseball team and an otaku.


 * Maaya Narasaka (奈良坂 真綾)
 * Saki's friend at school. She is always cheerful and meddlesome. She got increasingly involved with Saki because she could not stand to see her isolated, and later became her friend.
 * Saki's friend at school. She is always cheerful and meddlesome. She got increasingly involved with Saki because she could not stand to see her isolated, and later became her friend.


 * Shiori Yomiuri (読売 栞)
 * A university student who works part-time as a senior to Yuta at the bookstore.
 * A university student who works part-time as a senior to Yuta at the bookstore.


 * Taichi Asamura (浅村 太一)
 * Yuta's father and Saki's new step-father. After divorcing his ex-wife for various reasons, he re-married to Akiko. He has a good relationship with Yuta and Saki.
 * Yuta's father and Saki's new step-father. After divorcing his ex-wife for various reasons, he re-married to Akiko. He has a good relationship with Yuta and Saki.


 * Akiko Ayase (綾瀬 亜季子)
 * Saki's mother and Yuta's new step-mother. After divorcing her ex-husband, she worked tirelessly to provide for Saki until she re-married to Taichi.
 * Saki's mother and Yuta's new step-mother. After divorcing her ex-husband, she worked tirelessly to provide for Saki until she re-married to Taichi.

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; ten volumes have been released as of January 25, 2024.

At Sakura-Con 2023, Yen Press announced that they licensed the series for English publication.

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.

Anime
In July 2022, during the "Natsu no Gakuensai 2022" event for MF Bunko J, an anime television series adaptation was announced. The cast of the YouTube channel are reprising their roles. It is produced by Studio Deen and directed by Takehiro Ueno, with scripts written by Mitsutaka Hirota, characters designed by Manabu Nii, and music composed by Citoca. The series premiered on July 4, 2024, on AT-X and other networks. The opening theme song is "Tenshi-tachi no Uta" (天使たちの歌) performed by Fhána, while the ending theme song is "Suisō no Blanco" (水槽のブランコ) performed by Kitri. Crunchyroll licensed the series.

Reception
In the 2022 edition of Takarajimasha's annual light novel guide book Kono Light Novel ga Sugoi!, the novel series ranked 7th in the bunkobon category, and 3rd in the new work category. By January 2024, the series had over 600,000 copies in circulation.