Yukari Mutsuki is Nana Chigusa's close friend, though her gossiping nature makes her untrustworthy with secrets. Despite this flaw, she displays sharp perceptiveness toward unusual situations, especially concerning Nana. She swiftly detects a hidden depth to Nana's relationship with Kaoru Sugimura beyond their childhood history, though its exact nature puzzles her. Yukari also questions Nana's uncanny stress resilience and effortless management of heavy burdens. The possible connection between these two mysteries escapes her.

Her personality leans superficial and occasionally snaps at others, including Nana, whose pride ensures she never backs down in their clashes. Yet their conflicts dissipate rapidly, leaving no lasting bitterness between them.