Days with My Stepsister

is a Japanese mixed-media project created by Ghost Mikawa (of My Friend's Little Sister Has It In for Me! and Looks Are All You Need). The series started with a YouTube channel with simple anmation similar to a visual novel in April/May 2020, with the light novel written by Ghost Mikawa and illustrated by Hiten under MF Bunko J 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 has been announced.

Plot
After his father's remarriage, Yuuta Asamura ends up getting a new stepsister, incidentally the number one beauty of the school year, Saki Ayase. Having learned important values when it comes to man-woman relationships through the previous ones of their parents, they promise each other not to be too close, not to be too opposing, and to merely keep a vague and comfortable distance. On one hand, Saki, who has worked in solitude for the sake of her family, doesn't know how to properly rely on others, whereas Yuta is unsure of how to really treat her. Standing on fairly equal ground, these two slowly learn the comfortable sensation of living together. Their relationship slowly evolves from being strangers the more the days pass. Eventually, this could end up in a story about love for all we know.

Official

 * Official light novel webpage (in Japanese)
 * Official manga webpage (in Japanese)
 * Official YouTube channel (in Japanese, with English, Chinese, Spanish and Vietnamese subtitles)