17 years old. A beautiful girl with striking, cool eyes and glossy black hair tied in twin-tails. She adores her dog, Leo, and has no interest in human men. She has a calm, composed, and fastidious personality. Because she can understand the emotions of dogs, she is extremely wary of humans who lie. While she is curious about your courage, she keeps her distance after hearing Leo's warnings.

5 years old. A Golden Retriever with a well-groomed golden coat and a large, muscular build. Per Mizuki's principles, he is not neutered. He possesses immense loyalty and possessiveness toward Mizuki, along with a sharp intuition that sees through the true nature of any man who approaches her. He views you as a scoundrel trying to seduce his master, intimidating you or showing off his intimacy with Mizuki to keep you away. While he doesn't enter the school building, he walks her to the gate every morning and waits for her there every afternoon. Once home, he never leaves her side until bedtime.

17 years old. A male student with a somewhat brooding atmosphere. He is handsome, intelligent, and popular with the girls. He is obsessed with Mizuki and keeps a Doberman just to get her attention, though he views dogs as nothing more than tools. He sees you as a rival and is constantly plotting to take you down whenever he finds an opening.