Ikumi Tachikawa is a character from the original Comic Party series who also appears in its sequel, Comic Party: Revolution. In the original storyline, she is introduced as a mysterious and somewhat sickly young girl who becomes the first true fan of the protagonist, Kazuki Sendo, after discovering his artwork at a high school exhibition. Her early interactions with Kazuki are notably indirect; she initially communicates with him only through email under the name Tachikawa-san, supporting his burgeoning passion for creating doujinshi. She maintains her anonymity despite showing her support in tangible ways, such as sending him gifts and leaving items at his table during comic conventions.

In contrast to this secretive persona from the original game and anime adaptation, Ikumi in Comic Party: Revolution takes on a more defined but still supporting role as part of the returning cast. The series advances the timeline with the characters now in college, and Ikumi is present within this familiar group. While much of the focus in Revolution shifts toward new characters, Ikumi retains her core personality traits: she is gentle, reserved, and deeply supportive of her friends, showcasing a quiet but sincere strength. Her most significant narrative connection in Revolution is through her older brother, Yuuzo Tachikawa, who is introduced as a new character. Yuuzo is portrayed as large, strong, and almost entirely silent, creating a distinct contrast to Ikumi's more expressive and delicate demeanor. Their sibling relationship adds a new layer to her character, as Yuuzo often appears as a silent, protective presence.

As a character, Ikumi's primary motivation remains rooted in her appreciation for creativity and her desire to encourage those she believes in. She is not a loud or attention-seeking figure but finds fulfillment in quietly fostering the talents of others, a role she has filled for Kazuki since the beginning. Within the story of Comic Party: Revolution, she serves as a gentle and stabilizing influence among the cast, representing the loyal fanbase and the personal connections that make the creative community meaningful. Her relationship with Kazuki has evolved from that of an anonymous admirer to a reliable friend, though she retains her characteristic modesty. One of her notable abilities is her insightful understanding of art and storytelling, which first allowed her to recognize Kazuki's potential. Rather than possessing any flamboyant skills, her most consistent and defining ability is her unwavering kindness and her talent for offering heartfelt, meaningful encouragement to her friends.