Ep 4. My Little Sister Can't Be Going to Summerket

Kyosuke discovers that Kirino is secretly planning to attend a doujinshi event called Summerket, which features fan-made manga and merchandise. Despite her passion for anime and manga, Kirino is hesitant to attend due to societal stigma against otaku culture. She enlists Kyosuke's help in covering for her absence from a family event and attending Summerket under the guise of a study group with her classmates.

Kyosuke reluctantly agrees to help Kirino, even though he doesn't fully understand her obsession with anime and manga. However, their plan hits a snag when Kirino's best friend Ayase, who disapproves of otaku culture, shows up at the same event with her own group of friends. Kyosuke and Kirino scramble to avoid being seen by Ayase, while also navigating the overwhelming crowds and vendor booths at Summerket.

Throughout the course of the day, Kyosuke gains a deeper understanding of Kirino's passion for anime and manga, as well as the struggles she faces in hiding her interests from others. He also learns more about the wider otaku subculture, including the various subgenres of anime and manga and the fan communities that form around them.

As the day draws to a close, Kyosuke and Kirino successfully evade Ayase's notice and return home, exhilarated from their secret adventure. However, Kyosuke is left with newfound admiration for Kirino and a sense of guilt for not fully understanding her interests sooner. He realizes that there is more to his little sister than he ever imagined, and begins to question the societal norms that stigmatize otaku culture.

Overall, "My Little Sister Can't Be Going to Summerket" is a lighthearted and comedic exploration of the intersection between family relationships, societal expectations, and otaku culture. Through the perspective of Kyosuke, viewers are invited to question their own prejudices and biases, and to consider the importance of embracing oneself and one's passions.