Imouto sae Ireba Ii.

Popular novelist Itsuki struggles with writer's block while hosting friends for a dinner and game night.

Itsuki Hashima is a successful young author known for featuring little sisters in his stories, which causes him creative difficulties. His step-brother Chihiro, colleagues Hayato Fuwa and Nayuta Kani, and college student Miyako Shirakawa visit his apartment. The group shares dinner and drinks while playing a game. During the evening, Nayuta Kani makes romantic advances toward Itsuki Hashima. The source material ends abruptly at this moment without revealing the outcome of the interaction or further plot developments. The narrative focuses on this specific gathering and the interpersonal dynamics between the characters during their time together at the novelist's residence.

Nayuta and Miyako encounter Itsuki practicing a sister role while naked.

Nayuta and Miyako discover Itsuki naked before a bathroom mirror, attempting to embody the little sister character for his latest novel volume. Nayuta holds deep affection for Itsuki, while Miyako harbors secret romantic feelings for him. Despite this, Nayuta values Miyako for her past compassion during a difficult time. Nayuta invites Miyako to her hotel and promptly undresses, requesting that Miyako do the same to assist with research for her novel.

Itsuki and friends travel to Okinawa for research before heading to Hokkaido for food

Itsuki, Nayuta, and Miyako struggle with the cold weather and travel to Okinawa. They visit a remote island where Itsuki conducts research while Nayuta swims naked in the water. Miyako observes this scene, becomes amazed, and subsequently joins them in the water without clothing. Two days later, Itsuki receives an invitation from his illustrator to visit Hokkaido. During this trip, they sample various local dishes. However, the outing is interrupted when Itsuki discovers that Setsuna has been ignoring a deadline. The group faces this new complication after their initial relaxation and research activities in the southern locations.

Nayuta, Miyako, and Haruto gather for Valentine's Day while a new figure inspects Itsuki's possessions.

Nayuta, Miyako, and Haruto meet at Itsuki's room for Valentine's Day, where Haruto attempts to demonstrate his close bond with Itsuki once more. Toki arrives with chocolates sent by fans. A few days later, an unfamiliar individual appears at Itsuki's residence. As Itsuki prepares to file his final tax return, this new person carefully examines all of his belongings. The visit coincides with the administrative process of settling his financial affairs, leading to a thorough inspection of his property by the stranger who has suddenly entered his home.

Itsuki flees editor Toki to hot springs with Setsuna but encounters a shocking scene.

Itsuki is approaching the deadline for volume 5 and attempts to evade his editor, Toki, but is quickly caught. He manages to escape by running into Setsuna, and the two head to a hot springs. Setsuna admits he is in a creative slump and hopes to find inspiration by looking at women. However, upon arriving at the inn, Itsuki witnesses a horrifying sight that disrupts their plans.

Itsuki meets Kaiko Mikuniyama for the Mahou Academy manga adaptation

Itsuki meets Kaiko Mikuniyama, the manga artist adapting Mahou Academy. She appears refined, making him nervous, but shares his love for little sisters. The group celebrates the upcoming broadcast of Haruto's anime and the manga version of Itsuki's series. They gather to watch the first anime episode live, but unexpected events occur during the viewing.

Itsuki organizes a TRPG session to lift Haruto's spirits after his anime flop.

To cheer up Haruto following the failure of his anime, Itsuki gathers him, Nayuta, Miyako, and Chihiro to play a tabletop role-playing game. Although Itsuki typically portrays female characters, Chihiro interprets their roles as sisters to Itsuki's character. Consequently, Nayuta and Miyako also design their characters as siblings to the others. Haruto takes on the role of the Game Master, exercising his authority to do as he pleases within the game's framework.

Itsuki helps Haruto confess to Miyako while Nayuta plans a birthday party

Haruto shares his feelings for Miyako with Itsuki, who agrees to assist him. Simultaneously, Nayuta, who regards Miyako as a sister, expresses her desire to organize a birthday celebration for her. The two boys struggle to select an appropriate present, leading Nayuta to inquire about Miyako’s favorite author. Upon learning that Itsuki is the answer, Nayuta experiences jealousy for the first time due to their shared profession as authors. The narrative focuses on the gift selection process and the emerging rivalry between the two friends.

Introduction of Mikuniyama Kaiko and the theme of nudity and underwear

This segment focuses on the introduction of the character Mikuniyama Kaiko. The narrative centers on her arrival and initial presentation within the story context. The title suggests that themes regarding nudity and underwear are central to this specific episode's content, highlighting these elements as primary components of the plot or character dynamics presented here.

Having no problems is all that is required.

Becoming the Protagonist Is All You Need.

Is a Sister All You Need?