Miki Mizuguchi is a supporting character in the manga and anime series Whisper Me a Love Song. She is a first-year high school student and a member of the school's brass band club. Miki has long black hair that she holds in place with a hairpin on her bangs, green eyes, and a distinctive beauty mark near her mouth. She has been a close friend and classmate of Himari Kino since elementary school, and the two share a warm, easygoing bond. Miki is also the younger sister of Aki Mizuguchi, the bassist of the band SSGIRLS, and she deeply looks up to her older sister, often showing an enthusiastic, almost fangirl-like admiration for her. Despite being the same age as Himari, Miki tends to take on a more mature, reliable role in their friendship, frequently offering guidance and emotional support. Her personality is characterized by sharp wit, perceptiveness, and a caring but occasionally teasing nature. She is observant and skilled at gathering information, which she uses to indirectly help Himari and Yori Asanagi navigate their developing relationship. Miki acts as a confidante and love-life advisor for Himari, encouraging her to pursue her feelings while also being sensitive to the complexities surrounding her sister's past. Her primary motivation is to support her friends and her sister, and she often mediates situations with a level-headed, good-humored approach. In the story, she serves as a catalyst for Himari's romantic journey, providing both practical assistance and emotional reassurance. Her musical involvement in the brass band club highlights her own interests and abilities, though she remains focused on supporting those around her. Throughout the series, Miki consistently demonstrates loyalty and maturity, deepening her relationships with Himari and others without undergoing a major character shift, instead solidifying her role as a dependable friend and sister.