Chinatsu Hayakawa is a character from the anime My Tiny Senpai, serving as a colleague and childhood friend to the protagonist, Takuma Shinozaki. She is a young woman with neck-length blonde hair, often styled with bangs swept to the left, and brown eyes. Her birthday is on October 9.

Within the story, Chinatsu works in the design department of the same company as Takuma, having joined the firm at the same time as him. On the surface, she presents a personality that is straightforward, frank, and clear-cut in her communication, not hesitating to express her opinions directly. This can sometimes come across as blunt, especially in her interactions with her long-time friend Takuma, whom she often turns down or gives the cold shoulder, though this behavior masks a deeper, unspoken care for him as her oldest friend.

Beneath her professional and candid exterior, Chinatsu harbors a significant secret: she is an otaku with a deep passion for cosplay and creating doujinshi, specifically Boys' Love manga. She keeps this hobby hidden from almost all of her colleagues, with Takuma being the sole exception. This hidden side of her life is a core part of her character, showcasing her creativity and organizational skills in crafting costumes and preparing for fan events.

Her key relationships define much of her role in the narrative. Her dynamic with Takuma Shinozaki is rooted in a long history, having attended the same schools from daycare through to their office jobs. Despite their closeness, they describe their bond as a "腐れた縁" or a "corrupt bond," insisting there are no romantic feelings between them, as each is focused on other people. Nevertheless, their long history means they understand each other well, and they are among the few who can handle Takuma's sister, Yutaka.

Her most significant relationship is with her senior colleague, Chihiro Akina. Chinatsu's feelings for Chihiro are complex. She first fell in love with him during a job interview when he helped her fix a broken shoe, an act of kindness that left a lasting impression. Although she later got the job, she claims to have cooled off from that initial crush due to his oblivious and often frustrating behavior, and she keeps her past feelings hidden. However, her true emotions frequently betray her, as she often finds herself blushing and flustered by Chihiro's unintentional words and actions. This hidden affection takes a new turn when Chihiro accidentally discovers her cosplay hobby. Instead of reacting with judgment, he becomes unexpectedly supportive, helping her with her doujinshi creations and assisting at sales events, which deepens their unique connection. In future story developments, Chinatsu ultimately marries Chihiro.

Chinatsu's notable abilities lie in her creative talents. She excels at designing and creating cosplay costumes and writing doujinshi manga, a hobby she pursues with dedication and organizational skill. Her journey involves a gradual development from keeping her passions entirely secret to sharing them with Chihiro, leading to a supportive partnership. A small but telling detail about the character is that in earlier webcomic versions, her name was Chika, and some characters, like Yutaka Shinozaki, continue to call her by this nickname out of familiarity.