I Kissed My Girlfriend's Little Sister?!

I Kissed My Girlfriend's Little Sister?! (カノジョの妹とキスをした.) is a Japanese light novel series written by Riku Misora and illustrated by Saba Mizore. SB Creative published the series in four volumes from April 2020 to September 2022. A manga adaptation, illustrated by Kakito Kato, began serialization on the Manga UP! website in May 2022. As of October 2023, the manga's individual chapters have been collected into two volumes.

Light novel
Written by Riku Misora and illustrated by Saba Mizore, the series began publication under SB Creative's GA Bunko light novel imprint on April 14, 2020. The series was completed in its fourth volume, which released on September 14, 2022.

Tentai Books is publishing the series in English.

Manga
A manga adaptation, illustrated by Kakito Kato, began serialization on Square Enix's Manga UP! website on May 28, 2022. As of October 2023, the series' individual chapters have been collected into two tankōbon volumes.

Reception
In the 2021 edition of the Kono Light Novel ga Sugoi! guidebook, the series ranked eighth in the bunkobon category and fifth in the new work category.

Thomas Knight of NookGaming praised the setting and contrast between the two love interests in a review of the light novel and Tentai Books stated that I Kissed My Girlfriend's Little Sister?! has sold better than any of their other titles to date in an interview.